TWI486688B - Va type liquid crystal display device - Google Patents

Description

VA type liquid crystal display device

The present invention relates to a VA (Vertically Aligned) liquid crystal display device in which front contrast is improved.

In recent years, high contrast (CR) of liquid crystal display devices is progressing. In particular, compared with other modes, the VA liquid crystal display device has a high CR in the normal direction (hereinafter referred to as "front CR"), and various research and developments to improve its advantages are being improved. Keep on going. As a result, in the past six years, the front CR of the VA liquid crystal display device has been increased by about 20 times from about 400 to about 8,000.

On the other hand, in the liquid crystal display device, it is important that the front CR is high and the CR in the oblique direction (hereinafter referred to as the "viewing angle CR") is high. In the VA type liquid crystal display device, a retardation film has been proposed as a technique for reducing light leakage caused by an oblique direction in black display (for example, JP-A-2006-184640). In general, the liquid crystal cell is centered, and a retardation film is disposed on the front side and the rear side, respectively, and the two phase retardation films respectively share the phase difference necessary for optical compensation to achieve optical compensation. Two methods are generally used in the combination of optical compensation. One of the modes is a method of equally sharing the phase difference on the retardation film disposed on the front side and the rear side, and has only one advantage in the film to be used. Another way is to share a larger phase difference on the retardation film disposed on one side, which is advantageous in terms of cost and in combination with an inexpensive film and optical compensation. In the latter method, it is practical to use a phase difference film disposed on the rear side to share a larger phase difference. The reason for this is the manufacturing cost. For this reason, in the column [0265] of JP-A-2006-241293, "the cellulose of the present invention is used only on the protective film of the one side polarizing plate (between the liquid crystal cell and the polarizing film). In the case of a film, it may be either one of the upper polarizing plate (observation side) and the lower polarizing plate (backlight side), and there is no problem in function. However, since it is used as the upper polarizing plate, it is on the observation side. (The upper side) is necessary for providing a functional film, and there is a possibility that the productivity is lowered. Therefore, it is considered that the case where the lower polarizing plate is used is relatively high, and it is considered to be a description of a preferred embodiment. The second reason is that the film having a large phase difference is disposed on the rear side, and is preferably in terms of environmental resistance such as impact resistance, temperature change, and humidity change.

Heretofore, there has been no review of the relationship between the optical characteristics of the retardation film (retardation film) used for the comparison of the viewing angles and the positive CR.

In the case of a liquid crystal display device having a high CR, it is difficult to achieve a higher contrast system based on the proposed method for reducing the CR. As a result of intensive review, the present inventors have found that in the case of a VA liquid crystal display device, the hysteresis value of the retardation layer existing between the rear side polarizer and the liquid crystal cell is not considered to affect the front surface CR. It is one of the reasons for the decrease in the front CR.

The present invention has been made in an effort to provide a VA liquid crystal display device having a high front contrast.

The means for solving the above problems are as follows.

[1] A VA liquid crystal display device comprising a front side polarizer, a rear side polarizer, a VA type liquid crystal cell disposed between the front side polarizer and the rear side polarizer, and a rear side polarizer In the first phase difference region composed of one or two or more retardation layers between the VA liquid crystal cells, the first phase difference region satisfies the following formula:

0nm≦Re(590)≦10nm, and |Rth(590)|≦25nm

In the formula, Re (λ) means an in-plane hysteresis value (nm) at a wavelength λ nm, and Rth (λ) means a hysteresis value (nm) in a thickness direction of a wavelength λ nm.

[2] The VA type liquid crystal display device of [1], wherein the VA type liquid crystal cell has a front substrate and a rear substrate, and a ratio (CR _f / CR _r ) of a component contrast (CR _f ) of the front substrate The member contrast (CR _r ) of the rear side substrate is 3 or more.

[3] The VA liquid crystal display device according to [1] or [2], wherein the front side polarizer and the VA type liquid crystal cell have a second phase composed of one or two or more retardation layers. The difference field, and the second phase difference field satisfies the following formula:

30 nm ≦Re (590) ≦ 90 nm, and

170 nm ≦ Rth (590) ≦ 300 nm.

[4] The VA liquid crystal display device according to [3], wherein the first and second phase difference domains satisfy the following formula:

Δnd(590)-70≦Rth ₁ (590)+Rth ₂ (590)≦Δnd(590)-10

In the formula, d is the thickness (nm) of the liquid crystal layer of the VA type liquid crystal cell, and Δn (λ) is the refractive index anisotropy of the liquid crystal layer of the VA type liquid crystal cell at the wavelength λ, and Δnd(λ) means Δn (λ) is a product of d; Rth ₁ (λ) means a hysteresis value (nm) in the thickness direction of the first phase difference region of the wavelength λ, and Rth ₂ (λ) means the aforementioned wavelength λ. The hysteresis value (nm) in the thickness direction of the second phase difference field.

[5] The VA liquid crystal display device according to any one of [1] to [4] wherein the first phase difference field is composed of a deuterated cellulose-based film or a deuterated cellulose-based film.

[6] The VA liquid crystal display device according to [5], wherein the deuterated cellulose-based film contains at least one kind of hysteresis value Rth in the thickness direction within a range satisfying the following formulas (I) and (II). compound of,

(I) (Rth[A]-Rth[0])/A≦-1.0

(II) 0.01≦A≦30

(Rth[A]: Rth (nm) of a film containing A% of a compound which lowers Rth, Rth[0]: Rth (nm) of a film which does not contain a compound which lowers Rth, and A: film raw material polymer The mass is taken as the mass (%) of the compound at 100 hours).

[7] The VA type liquid crystal display device according to [5] or [6], wherein the deuterated cellulose-based film is in a deuterated cellulose having a thiol substitution degree of 2.85 to 3.00, relative to the deuterated cellulose solid. The content contains at least one compound having an in-plane hysteresis value Re and a thickness direction hysteresis value Rth of 0.01 to 30% by mass.

[8] The VA type liquid crystal display device according to any one of [5], wherein the deuterated cellulose film is at least 0.01 to 30% by mass based on the solid content of the deuterated cellulose. One compound which lowers |Re(400)-Re(700)| and |Rth(400)-Rth(700)| of the film.

[9] The VA liquid crystal display device according to any one of [1] to [8] wherein the first phase difference region is composed of an acrylic polymer film or an acrylic polymer film.

[10] The VA type liquid crystal display device of [9], wherein the first phase difference region is an acrylic acid containing a unit selected from at least one selected from a lactone ring unit, a maleic anhydride unit, and a glutaric anhydride unit. It is composed of a polymer-based acrylic polymer film or has the acrylic polymer film.

[11] The VA liquid crystal display device according to any one of [3] to [10] wherein the second phase difference field is composed of a deuterated cellulose film or a deuterated cellulose film.

[12] The VA liquid crystal display device according to any one of [3], wherein the second phase difference region is composed of a cyclic olefin polymer film or a cyclic olefin polymer film. .

[13] The VA type liquid crystal display device according to any one of [1] to [12] wherein the front contrast is 1500 or more.

[14] The VA type liquid crystal display device according to any one of [1] to [13], which is a backlight unit including three primary colors of light which are sequentially illuminated independently, and is driven by a Field Sequential driving method. of.

Effect of invention

According to the present invention, it is possible to provide a VA type liquid crystal display device having a high front contrast.

Form of implementing the invention

Hereinafter, the present invention will be described in detail. In addition, the numerical range represented by "~" in this specification means the numerical value contained in the before and after "~" as a range of a lower limit and an upper limit.

First, the terms used in this specification will be explained.

(hysteresis value, Re and Rth)

In the present specification, Re(λ) and Rth(λ) each indicate an in-plane hysteresis value (nm) at a wavelength λ and a hysteresis value (nm) in a thickness direction. In the KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments Co., Ltd.), Re (λ) is measured by causing light having a wavelength of λ nm to enter the normal direction of the film. The standard wavelength of KOBRA is 590 nm.

In the case where the sample such as the film to be measured is represented by a refractive index ellipsoid of one axis or two axes, Rth(λ) is calculated by the following method.

Rth(λ) is the above-mentioned Re(λ) as the in-plane slow axis (determined according to KOBRA 21ADH or WR) as the tilt axis (rotation axis) (the case without the late phase axis is in any direction in the film plane) The normal direction of the film of the rotating axis) is from the normal direction to 50 degrees on one side at a pitch of 10 degrees, and the light of the wavelength λ nm is incident from the direction of each of the tilts, and all of the light is measured at 6 points, and the hysteresis value is measured according to the same. The KOBRA 21ADH or WR is calculated from the assumed value of the average refractive index and the input film thickness value.

In the above, in the case where the in-plane slow axis from the normal direction is regarded as the rotation axis and the film having the retardation value in a certain inclination angle is zero, the inclination angle is larger than the inclination angle. After the hysteresis value is changed to a negative sign, KOBRA 21ADH or WR is calculated.

In addition, the slow phase axis is regarded as the tilt axis (rotation axis) (the case where there is no slow phase axis is regarded as the rotation axis in any direction in the film plane) and the hysteresis value is measured from the 2 directions of any inclination, and the value is averaged according to the value The assumed value of the refractive index and the input film thickness value can also be calculated from the following formula (X) and formula (XI).

Formula (XI)

Rth={(nx+ny)/2-nz}×d

Note:

The above Re(θ) represents a hysteresis value in the direction of the inclination angle θ from the normal direction. Further, in the formula, nx represents a refractive index in the in-plane axial axis direction, ny represents a refractive index orthogonal to the nx direction in the plane, and nz represents a refractive index orthogonal to the nx and ny directions. d is the film thickness.

In the case where the film to be measured cannot be represented by a refractive index ellipsoid of one axis or two axes and a film having no optical axis (optic axis), Rth(λ) is calculated by the following method.

Rth(λ) is the film normal direction of the film in the in-plane retardation axis (determined according to KOBRA 21ADH or WR), from -50 degrees to +50 degrees. At a pitch of 10 degrees, light having a wavelength of λ nm was incident from the direction of the tilt, and 11 points were measured, and KOBRA 21ADH or WR was calculated according to the measured hysteresis value and the assumed value of the average refractive index and the input film thickness value.

In the above measurement, the assumed value of the average refractive index is a catalogue value of a polymer handbook (JOHN WILEY & SONS, INC) and various optical films. Regarding the value of the average refractive index unknown, it can be measured by an Abbe refractometer. The values of the average refractive index of the main optical films are exemplified as follows:

Deuterated cellulose (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), polystyrene (1.59).

Nx, ny, and nz are calculated by KOBRA 21ADH or WR by inputting the assumed value of the average refractive index and the film thickness. Further, Nz = (nx - nz) / (nx - ny) is calculated based on the calculated nx, ny, and nz.

In the present specification, the "late phase axis" of a retardation film or the like means a direction in which the refractive index is the largest. In addition, the "visible light region" means 380 nm to 780 nm. In addition, in the present specification, in the case where there is no special note on the measurement wavelength, the measurement wavelength is 590 nm. The wavelength 590 nm is a wavelength generally used in the management of film physical property values in the industry to which the present invention pertains.

In the present specification, the numerical value, the numerical range, and the qualitative expression (for example, "equivalent", "equal", etc.) of the optical characteristics of each member, such as a phase difference field, a retardation film, and a liquid crystal layer, are described. It is to be understood that the numerical values, numerical ranges, and properties of the liquid crystal display device and the components used therein are generally included.

In the present specification, the retardation film means a film having self-supporting properties disposed between the liquid crystal cell and the polarizer (regardless of the magnitude of the hysteresis value). Further, the retardation film is synonymous with the retardation film. The phase difference field is a general term for a retardation film of one or two or more layers disposed between a liquid crystal cell and a polarizer.

In addition, in this specification, the "front side" means the display surface side, and the "back side" means the backlight side. In addition, the "front side" in this specification means the normal direction of the display surface, and the "front contrast (CR)" is calculated from the white brightness and the black brightness measured in the normal direction of the display surface. Compared.

The present invention relates to a VA liquid crystal display device characterized in that the VA type liquid crystal cell and the rear side polarizer have a first phase difference region satisfying the following formula.

0nm≦Re(590)≦10nm, and |Rth(590)|≦25nm

Heretofore, the light source of the liquid crystal display device uses a backlight that illuminates light having directivity as a backlight disposed on the rear side. The light from the liquid crystal display device obliquely incident on the liquid crystal display device is scattered in the liquid crystal cell and the color filter in the liquid crystal cell, and the component scattered in the front direction is one of the causes of lowering the front surface CR. As a result of the review by the inventors, it is found that the light from the backlight incident on the rear side polarizer enters the liquid crystal cell, and the decrease in the front surface CR in the phase difference region becomes remarkable. The reason is as follows.

(i) The linearly polarized light from the backlight obliquely incident and passing through the back side polarizer is polarized by the Re and/or Rth in the phase difference field before passing through the phase difference field before entering the liquid crystal cell. Then, it is scattered to the front side due to the liquid crystal layer, the color filter layer, and the like in the liquid crystal cell. Among the light that is scattered on the front side, the component in the absorption axis direction of the front side polarizer (hereinafter referred to as "A component") is absorbed by the polarizer, but the component of the front side polarizer in the transmission axis direction (below) There is a case called "B component", and a polarizer is passed. This B component is responsible for reducing the front CR. If the B component is reduced, the front contrast can be improved. From this viewpoint, the smaller the Rth system in the phase difference region between the rear side polarizer and the liquid crystal cell, the better.

In addition,

(ii) In the retardation film constituting the phase difference region, the distribution of the optical axis is produced, and the axial shift occurs when it is bonded to the polarizer. Since the axis offset promotes the circular polarization of the light from the backlight, the front contrast can be improved if the axis offset is reduced. In the case of this viewpoint, the Re system which is disposed in the phase difference region between the rear side polarizer and the liquid crystal cell is preferably as small as possible.

Based on the above findings (i) and (ii), it was found that a VA type liquid crystal display device having a high front CR can be obtained by satisfying the following equation by the first phase difference between the rear side polarizer and the liquid crystal cell. And achieved the completion of the present invention.

And

That is, according to the present invention, by forming the above configuration, it is possible to provide a VA type liquid crystal display device which achieves high frontal contrast. Further, in the present invention, since only a phase difference film having a low Re and a low Rth is disposed in the phase difference between the rear side polarizer and the liquid crystal cell, the polarizer is deformed by heat from the backlight, and the like. The retardation film is increased in stress, but the change in the optical anisotropy of the phase difference film of the low Re and low Rth does not reach the limit. As a result, in the conventional VA liquid crystal display device, light leakage occurring at the four corners of the screen, and a so-called failure in which the display quality of the corner mura is lowered can be alleviated.

Further, in the second phase difference region between the front side polarizer and the liquid crystal cell, in the aspect of displaying a predetermined optical characteristic, it is possible to provide CR which can increase the oblique direction and reduce color shift when black display is performed (color Shift) liquid crystal display device.

Fig. 1 is a schematic cross-sectional view showing an example of a VA liquid crystal display device of the present invention. Further, in the drawings, the relative relationship of the thicknesses of the respective layers does not necessarily coincide with the relative relationship of the thicknesses of the respective layers of the actual liquid crystal display device.

The VA liquid crystal display device shown in Fig. 1 has a VA type liquid crystal cell LC, and a rear side polarizing plate PL1 and a front side polarizing plate PL2 sandwiching the same. The backlight 10 is disposed on the outer side of the rear side polarizing plate PL1, and the light from the backlight 10 is configured to enter in the order of the rear side polarizing plate PL1, the liquid crystal cell LC, and the front side polarizing plate PL2. The liquid crystal cell LC is a liquid crystal cell of the VA mode, and becomes a vertical alignment when black is displayed. The liquid crystal cell LC is formed by arranging the upper substrate 26 and the lower substrate 24, which are made of glass or the like, and has an alignment film (not shown) and an electrode layer (not shown) on the substrate. A color filter layer (not shown) is provided on the substrate on the front side.

The rear polarizing plate PL1 has a polarizer 12, a first retardation film 16 and an outer protective film 20 on the surface thereof, and a front polarizing plate PL2, respectively, having a polarizer 14 and a second retardation film 18 on the surface thereof. And the outer protective film 22. The polarizers 12 and 14 are arranged such that their absorption axes are orthogonal to each other. The first retardation film disposed between the polarizer 12 of the rear polarizing plate PL1 and the liquid crystal cell LC is a retardation film satisfying 0 nm ≦ Re (590) ≦ 10 nm and |Rth (590) | ≦ 25 nm. In the range satisfying this characteristic, a plurality of retardation films may be present. For example, a protective film of the polarizer 12 may be separately disposed between the first retardation film 16 and the polarizer 12, but the phase difference between the first retardation film 16 and the protective film is equal to 0 nm ≦ Re (590). ≦10 nm, and |Rth(590)|≦25 nm. That is, a plurality of retardation films may be present between the polarizer 12 and the liquid crystal cell LC, but the total phase difference of the plurality of sheets satisfies the above characteristics. By satisfying the above characteristics by the retardation film disposed between the polarizer 12 and the liquid crystal cell LC, the VA type liquid crystal display device shown in FIG. 1 can suppress the oblique incident light from the backlight 10 before entering the liquid crystal cell LC. The roundness of the circle is polarized. As a result, the contrast reduction caused by the reasons (i) and (ii) above can be alleviated, and a high positive CR can be achieved.

The present inventors have focused exclusively the result of the review, the effect of the present invention are known in front substrate type liquid crystal cell of VA (including all member 26 formed on the substrate 1 in FIG substrate) of one member that is higher than the contrast CR _f rear The aspect of the substrate contrast (CR _r ) of the substrate (including the substrate 24 in Fig. 1 and all the members formed on the substrate) becomes particularly remarkable. Furthermore, the ratio of the component contrast (CR _r ) of the front side substrate to the CR ₁₁₅ of the rear side substrate (CR _f /CR _r ) is 3 or more, that is, in the case where the 3 ≦ CR _f /CR _r is known, The effects of the present invention become remarkable. Here, when the VA type liquid crystal cell (LC in FIG. 1) is decomposed in two sheets of substrates (substrates 24 and 26 in FIG. 1), the front side substrate (substrate 26 in FIG. 1) is formed on the substrate thereof. The general name of the members is referred to as a front substrate, and the substrate on the rear side (substrate 24 in FIG. 1) and the members formed on the substrate are collectively referred to as a rear substrate. Examples of the member include a color filter, a black matrix, an array member (such as a TFT array), a projection on a substrate, a common electrode, a slit, and the like, and various members. That is, the comparison of the members of the rear substrate and the front substrate of the liquid crystal cells refers to the comparison of the respective substrates and the various members formed on the respective substrates. The details of the measurement method are described in the examples to be described later.

As a result of intensive review by the present inventors, it is known that the hysteresis value in the field of the first phase difference between the back side polarizer and the liquid crystal cell greatly affects the front surface CR of the liquid crystal display device. This reason is due to the so-called scattering of liquid crystal cells in various members (for example, a liquid crystal layer, a color filter, a black matrix, an array member, a protrusion formed on a substrate, a common electrode member, a slit member, etc.). Optical phenomena with diffraction and polarization dependence for their optical phenomena. Hereinafter, it demonstrates in detail.

In general, since the liquid crystal layer is in a vertical alignment state when the VA liquid crystal display device is displayed in black, the polarization state does not change even after passing through the liquid crystal layer after the linear polarization of the rear side polarizer and moving in the normal direction. In principle, all of the absorption axes of the front side photons are absorbed. That is, it can be said that in principle, there is no light leakage in the normal direction in the black display. However, the front transmittance of the VA type liquid crystal display device at the time of black display is not zero. The reason for this is that the liquid crystal molecules in the liquid crystal layer are shaken, and it is known that light incident on the liquid crystal layer is scattered by a certain degree of shaking. When the light system incident on the liquid crystal layer does not completely contain the linearly polarized light component absorbed only by the absorption axis of the front side polarizer, the influence becomes larger, and the light leakage on the front side tends to increase. In other words, the larger the phase difference in the phase difference region disposed on the rear side, and the more the rounded polarized light is converted into a high circular polarization, the more the front light leakage caused by the shaking can be alleviated.

However, as a result of the review by the inventors, it is known that the phase difference in the phase difference region between the rear side polarizer and the liquid crystal layer is one of the causes, in addition to the shaking of the liquid crystal molecules in the liquid crystal layer. When a certain light from the directivity of the backlight passes through the rear side polarizer and enters the phase difference field from the oblique direction, the linearly polarized light is converted into a circularly polarized light due to the phase difference. The circular polarization is diffracted and scattered by the array member in the liquid crystal cell and the color filter layer, and at least a portion is light that advances in the front direction. Since the circularly polarized light contains a linearly polarized component that cannot be cut off by the absorption axis of the front side polarizer, it causes light leakage in the front direction and a decrease in the front surface CR even in the case of black display. The optical phenomenon generated by the array member and the color filter layer is not completely smooth, for example, on the surface of the array member and the color filter layer, and has a certain degree of unevenness or a scattering factor or the like in the member. The effect of the optical phenomenon generated by the array member and the color filter layer on the light leakage in the front direction is greater than the influence caused by the shaking of the liquid crystal molecules in the liquid crystal layer described above.

In addition, as a result of the intent of the present inventors, the inventors of the present invention have known that optical phenomena (diffraction, scattering, etc.) which are received by a predetermined component of the liquid crystal cell by the phase difference light field are obtained. The aspect in which light passes through the member before entering the liquid crystal layer or after passing through the liquid crystal layer, and affects light leakage in the front direction becomes different. In FIG. 1, for example, as shown in FIG. 2(a), an array member is disposed on the inner surface of the rear substrate 24, and when a color filter is disposed on the inner surface of the front substrate 26, light is incident on The liquid crystal layer passes through the array member before and passes through the color filter after passing through the liquid crystal layer.

The member (for example, the array member) that passes before the light enters the liquid crystal layer, the circular polarization of the incident light is determined by the phase difference in the front phase difference region (first phase difference region) passing through the light. On the other hand, a member (for example, a color filter) that passes after entering the liquid crystal layer is determined not only by the phase difference in the back phase difference region but also by the phase difference of the liquid crystal layer. Here, in the case of a liquid crystal display device for VA, Δnd (590) of the liquid crystal layer (thickness (nm) of the d-type liquid crystal layer, refractive index anisotropy of the liquid crystal layer at the wavelength λ, Δnd ( The λ) system Δn(λ) and d) is set at about 280 to 350 nm. It is also possible to set the phase difference in the area of the rear side phase difference so that the light leakage of the array member is reduced, and the rounding ratio becomes oppositely large when passing through the liquid crystal. Since the rounding ratio of the incident polarized light becomes smaller as the phase difference in the back phase difference region is larger, the rear side phase is set in accordance with the member that is incident on the light before passing through the liquid crystal layer or the member that is incident on the light after passing through the liquid crystal layer. The phase difference in the difference field, the result reverses the effect of the component on the light leakage in the front direction.

The tendency of the phase difference in the rear phase difference field, the tendency to affect the light leakage in the front direction by the respective members, and the influence of the influence thereof are summarized in Example 2 (b). In addition, in FIG. 2(b), "↑" indicates that the front side phase difference region can increase the effect of the front side CR as compared with the case of the high hysteresis value, and the "↓" system indicates that the front side CR is lowered. The number of arrows is the basis for their strength and strength. The more the number of roots, the stronger the effect.

As shown in FIG. 2(b), when a color filter is disposed on the front substrate and a VA liquid crystal display device in which the array member is disposed on the rear substrate, and the phase difference in the phase difference of the rear side is reduced, The optical phenomenon caused by the array member of the rear substrate causes the light leakage in the front direction to act in the mitigating direction, and on the other hand, the optical phenomenon caused by the color filter layer disposed on the front substrate is generated. The light leakage in the front direction acts in the direction of increase, that is, the relationship between the two sides is offset.

For example, in the same manner as the both sides of the rear substrate and the front substrate, the liquid crystal cell is formed as a member that causes a decrease in contrast, and the first phase difference region on the rear side is a low hysteresis value, and is also disposed. The member of the rear substrate (for example, the array member in FIG. 2(b)) functions to increase the front surface CR, or the member disposed on the front side substrate (for example, the CF member in FIG. 2(b)) reduces the front surface CR. Role, but there are a number of situations that are eliminated. In other words, the feature of the present invention in which the first phase difference region in the rear side is a low hysteresis value means that the rear substrate has a large number of members which cause a decrease in contrast, and is particularly high. effect.

Further, the influence of the hysteresis value in the first phase difference region on the rear side on the front surface CR is substantially negligible in the liquid crystal display device having a low front side CR. However, in the case of a liquid crystal display device having a high front CR (for example, a front CR of 1500 or more) which has been provided in recent years, the influence cannot be ignored in the case of further improving the front surface CR. The present invention is particularly useful for further improving the front surface CR for a liquid crystal display device having a front CR of 1500 or more.

2 is a view showing a configuration in which a color filter (CF) is formed on the inner surface of the front substrate 26 and a liquid crystal cell having an array member on the inner surface of the rear substrate 24 as an example, and is an example of the present invention. In the liquid crystal display device, the positions of the CF and the array member are arbitrary. For example, if the color filter is directly disposed on an array (COA, color filter on array), the aspect in which the CF is disposed on the side of the substrate side after the array member is of course also included in the present invention. Further, if the array member is disposed on the side of the front substrate 26, the function of the array member becomes the same as that of the CF member in Fig. 2(b), and if CF is disposed on the side of the rear substrate 24, the function of the CF member The system becomes the same as the array member of Fig. 2(b). The other members (for example, black matrix) not shown are the same. If the member is disposed on the side of the front substrate 26, the function of the array member becomes the same as that of the CF member in FIG. 2(b). If it is disposed on the side of the rear substrate 24, the function of the member becomes the same as that of the array member of Fig. 2(b).

As described above, it is known that the component contrast (CR _r ) ratio (CR _f /CR _r ) of the component comparison CR _f to the rear substrate (the substrate 24 in FIG. 1 ) on the front substrate (the substrate 26 in FIG. 1 ) is 3 or more, that is, a state in which 3≦CR _f /CR _r is satisfied, the effect of the present invention becomes remarkable. As an example of the liquid crystal cell satisfying the relationship, for example, the rear substrate is a liquid crystal cell of the COA substrate. The COA is described in detail in JP-A-2005-99499 and JP-A-2005-258004.

Further, as described above, the incident polarization state dependence of the light leakage at the time of black display due to the optical phenomenon in the CF, the black matrix, and the array member tends to be the same, but the contribution from the black matrix Since the CF is disposed on the side of the substrate side after the array member, the COA of the liquid crystal display device can be located at any position in the liquid crystal cell, preferably at the rear side polarizer and the liquid crystal layer. between.

Further, examples of the liquid crystal cell satisfying 3 ≦ CR _f /CR _r include, for example, liquid crystal cells having no color filter and liquid crystal cells driven by field sequential printing without color filters. The liquid crystal cell driven by the field sequential system is described in detail in JP-A-2009-42446, JP-A-2007-322988, and No. 3,996,178, and the like. The so-called field sequential driving system utilizes a backlight unit that sequentially emits independent three primary colors of light. A backlight unit having an LED is preferable as the light source. For example, a backlight unit having an LED element having three colors of red, green, and blue as a light source is preferably used.

In addition, an array member may be disposed on the rear substrate, and a liquid crystal cell of a general color filter may be disposed on the front substrate. If the contrast of the color filter is high, the above conditions are of course satisfied. 3 ≦ CR _f /CR _r is a preferred aspect of the invention. As an example of a high-contrast color filter, a color filter using a pigment having a smaller particle diameter can be used, for example, than a pigment used in CF. As an example of the production method of the color filter using the high contrast of the pigment, the following two methods are mentioned.

(I) A method of mechanically finely pulverizing pigment particles by using a disperser called a sand mill, a roll mill, or a ball mill, and is described in detail in JP-A-2009-144126, for example, and can be referred to. .

(II) A method of adjusting the fine pigment particles by dissolving the pigment in a solvent and then precipitating it is described in detail in JP-A-2009-134178.

In addition to pigments, a method of using dyes to produce high contrast color filters has also been proposed. It is described in detail in Japanese Laid-Open Patent Publication No. 2005-173532, which can be referred to.

By using such a highly contrasted color filter, even a general configuration can be a liquid crystal cell satisfying 3 ≦ CR _f /CR _r .

Further, in Fig. 1, the optical characteristics of the second retardation film 18 included in the front side polarizing plate PL2 are preferably used to improve the contrast in the oblique direction and to reduce the color shift in the black display. Further, the Δnd(λ) of the liquid crystal layer of the VA type liquid crystal cell LC is as described above, and is generally about 280 to 350 nm. The hysteresis value of the second retardation film 18, particularly the preferred range of Rth, can be varied in accordance with the value of Δnd (λ) of the liquid crystal layer. In order to improve the oblique contrast, a combination of a preferred retardation film for Δnd (λ) is described in various publications, and is described in, for example, Japanese Patent Nos. 3,282,986, 3,666,666 and 3,556,159, and the like. Reference.

The preferred range of the optical characteristics in the second phase difference field will be described later.

Further, Δnd (590) of the VA type liquid crystal cell is generally about 280 to 350 nm, in order to increase the transmittance at the time of white display as much as possible. On the other hand, when Δnd (590) is 280 nm or less, the white luminance is slightly lowered as the Δnd (590) is lowered. However, since the thickness d of the unit cell is small, the liquid crystal display having excellent high-speed response is obtained. Device. When the first retardation value in the rear side is a low hysteresis value, the light leakage in the front direction is reduced, and as a result of the present invention, a so-called high front CR is obtained, and any liquid crystal display device of Δnd (590) is used. It also has an effect.

The VA liquid crystal display device of FIG. 1 is an embodiment in which the first retardation film 16 and the second retardation film 18 respectively function as protective films for the polarizers 12 and 14, but the present invention is not limited to this embodiment. form. For example, a protective film of a polarizer may be disposed between the first retardation film and the second retardation film and the polarizers 12 and 14, respectively. However, as described above, the protective film disposed between the first retardation film and the polarizer 12 is required to satisfy the characteristics obtained in the first phase difference field as all of the laminates of the first retardation film.

In addition, the rear side polarizer 12 has a protective film 20 on the surface of the backlight 10 side thereof, and further has a function of an antifouling film, an antireflection film, an anti-glare film, an antistatic film, and the like on the surface thereof. In addition, the front side polarizer 14 has a protective film 22 on its display surface side surface, and may further have an antifouling film, an antireflection film, an antiglare film, an antistatic film, etc. on the surface thereof. Functional film.

However, as described above, in the case where a large phase difference is shared on one side to perform optical compensation, a film having a large phase difference is conventionally disposed on the rear side, but is generally disposed on the front side as in the present invention. It is considered that the yield as a polarizing plate can be improved. Explain the reason.

Since a film having a large phase difference must be stretched at a high magnification, an inexpensive film which can be produced even without adding a large amount of additives to the film (so-called plane TAC=Re is 0 to 10 nm, and Rth is 30 to 80 nm). It is difficult to widen the film compared to a film having a small phase difference compared to a film of a triacetyl cellulose film or the like. In a general liquid crystal display device, a liquid crystal cell in a lateral direction is used, and generally, an absorption axis of a front side polarizer is arranged in a horizontal direction (left-right direction), and an absorption axis of a rear side polarizer is arranged in a vertical direction (up-and-down direction). Further, in industrial production, a polarizing film and a retardation film are generally bonded by a roll-to-roll method. In consideration of the fact that the polarizing plate produced in the production method is bonded to the liquid crystal cell, the film having a large phase difference is disposed on the front side, and the width direction of the polarizing plate can be used with high efficiency, that is, the yield can be improved. In the case where a retardation film having a small phase difference is disposed on the rear side as in the present invention, it is easy to make the film into a wide film, and the yield can be further improved by combining with a wide polarizer. As a result, the amount of discarded polarizing plates can be reduced.

Here, specific numbers are used for explanation. In general, the width of the retardation film is mostly 1100 mm, 1300 mm, 1500 mm, 2000 mm, and 2500 mm, and the thickness of the film is mostly 25 μm, 40 μm, and 80 μm. The roll length of the wound film is mostly 2500 m and 4000 m. On the other hand, if the screen size of the VA type liquid crystal display device is for television use, the screen size is 20 inches, 32 inches, 40 inches, 42 inches, 52 inches, 68 inches, and the like. For example, considering that the current market is mostly 42 inches, the 42-inch (standard 4:3) screen width is 853mm (42 inches wide and 16:9 is 930mm), and the picture height is 640mm (42 inches wide). 523mm). In the mode in which a film having a large phase difference is generally disposed on the rear side, for example, a retardation film of 1300 mm and 1500 mm width is used as a retardation film for one screen in the width direction. In this aspect, since a film having a large phase difference is disposed on the front side, for example, a retardation film of 1300 mm or 1500 mm width is preferably used in the width direction of the retardation film, so that two types of widths can be used. The phase difference film for the screen is nearly twice as productive. The size of the TV is increased year by year. For example, since the screen width of the 65-inch (standard) system is 991 mm and the height of the screen is 1321 mm, even in the conventional rear side configuration, even a wide-width 2000 mm film can be used in the width. In the direction, only the phase difference film for one screen is used. As in this aspect, the front side is a phase difference film for the two types of screens in the width direction. Further, since the screen width of the 68-inch (wide) screen is 1505 mm and the screen height is 846 mm, productivity of nearly twice as high can be expected.

The mode of the VA liquid crystal display device of the present invention may be any one, specifically, a MVA (Multi-domain Vertical Alignment) type or a PVA (Patterned Vertical Alignment) type. Any of Optical Alignment and PSA (Polymer-Sustained Alignment). The details of these modes are described in detail in JP-A-2006-215326 and JP-A-2008-538819.

As described above, a high contrast color filter can also be used in the present invention, and a color filter having a general liquid crystal display device can of course be used. In general, a color filter is a color filter in which a plurality of different colors (for example, three primary colors of red, green, and blue light, transparent, yellow, cyan, etc.) are arranged in a pixel portion of a substrate. There are various methods for producing the film, and generally, for example, a coloring material (organic pigment, dye, carbon black, or the like) is used to prepare a color-sensitive photosensitive composition (also in the case of colorless) which is called a photoresist. This was applied on a substrate to form a layer, and the pattern was formed by a lithography method. There are various methods for applying the coloring photosensitive composition to a substrate. For example, a spin coating method is used in the initial stage, and a slit & spin coating method is used from the viewpoint of liquid saving. Slit ‧ coating method. Further, there are a roll coating method, a bar coating method, a die coating method, and the like. Further, in recent years, after a pattern called a pixel separation wall is formed by a lithography method, a color of a pixel can be formed by an inkjet method. In addition, a method of combining a colored non-photosensitive composition and a photosensitive positive resist, a printing method, an electrodeposition method, a film transfer method, and the like are known. The color filter used in the present invention may also be produced by any method.

The material for forming the color filter is also not particularly limited. As the coloring material, any of a dye, an organic pigment, an inorganic pigment, and the like can also be used. The dyes have been reviewed based on the requirements of high contrast, and in recent years, the dispersion technique of organic pigments has been advanced, and finely crushed pigments such as salt milling methods or micronized pigments by the accumulation method have been used. High contrast. Any coloring material can also be used in the present invention.

In addition, the effect of the front contrast enhancement of the present invention can be further improved by adjusting the angular profile of the outgoing light from the backlight. Specifically, since the absolute value of the front contrast is increased when the backlight having a higher light collection property is used, the increase in the absolute value of the front CR shown in the present invention also becomes large. The indicator of the light collecting property is expressed, for example, by a ratio I (0°)/I (45°) of the emitted light intensity I (45°) at a polar angle of 45 degrees to the emitted light intensity I (0°) on the front side. When the value is larger, a so-called light collecting backlight is formed. As a backlight having a high light collecting property, it is desirable to provide a tantalum film (tantalum layer) having a light collecting function between the diffusion film and the liquid crystal panel. The tantalum film is a light-emitting surface that is emitted from the light-emitting surface of the light guide plate and diffused in the diffusion film, and is efficiently collected in an effective display region of the liquid crystal panel. A liquid crystal display device including a backlight of a general direct type is provided, for example, a liquid crystal panel including a color filter or a liquid crystal layer between a transparent substrate or a polarizing plate, and a backlight provided on a lower surface side thereof. Brightness Enhancement Film (BEF) is a representative example of the registered trademark of 3M Company of the United States. BEF is a film in which a unit of a triangular cross-sectional shape is periodically arranged in one direction on a film substrate, and the wavelength of germanium is large (pitch) compared with the wavelength of light. The BEF collects light from "off-axis" light and redirects or "recycles" the light toward the viewer on an "on-axis". As a patent document which discloses a brightness control member which has a repeating array structure in the 稜鏡 which is represented by the BEF, the display is a main point of the display, and many of the known patents are disclosed in Japanese Patent Publication No. Hei No. 1-37801 and Japanese Patent Publication No. Hei 6-102506. Japanese Patent Publication No. 10-506500.

Further, it is also desirable to use a lens array sheet in order to improve the light collecting property. The lens array sheet has a lens surface in which a plurality of unit lenses which are formed in a convex shape at a predetermined pitch are arranged in a second dimension. It is preferable that the opposite side of the lens surface forms a flat surface, and a lens array sheet in which light is reflected on the non-light-splitting surface of the lens is formed on the flat surface. Further, in order to form a lenticular lens surface in which a plurality of convex cylindrical lenses formed at a predetermined pitch are arranged in a parallel direction, the opposite side of the lens surface forms a flat surface, and the flat surface may be formed on the flat surface. A lens array sheet in which a light reflection layer of stripe light rays in a longitudinal direction is reflected in a non-light-splitting surface of the convex cylindrical lens. Further, for example, a lenticular lens array sheet in which unit lenses each composed of a cylindrical curved surface are arranged in one direction in the plane may be used, or a dome shape having a bottom shape having a circular shape, a rectangular shape, a hexagonal shape, or the like may be used. A unit lens composed of a curved surface, a lens array sheet in which two dimensions are arranged in the plane, and the like. The lens array sheet of the above-mentioned lens is disclosed in Japanese Laid-Open Patent Publication No. Hei No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. It is described in each of the publications of JP-A-2007-41172, and can be referred to.

The present invention can also exhibit an effect in the aspect of the display in which the color reproduction domain is expanded by adjusting the spectrum of the emitted light of the backlight and the transmission spectrum of the color filter. Specifically, it is preferable to use a white backlight that combines and mixes a red LED, a green LED, and a blue LED in a backlight. In addition, the half value of the peak of the outgoing light of the red LED, the green LED, and the blue LED is preferably small. In the case of an LED, the half-value wavelength range is as small as about 20 nm compared with the CCFL, and the peak wavelength is R (red) to 610 nm or more, G (green) to 530 nm, and B (blue) to 480 nm or less. Improve the color purity of the light source itself.

Further, it has been reported that, in addition to the peak wavelength of the LED, the color transmittance of the color filter can be further reduced and suppressed, and the color reproducibility can be further improved, and the NTSC ratio can have a characteristic of 100%. For example, it is described in Japanese Laid-Open Patent Publication No. 2004-78102. The red color filter preferably has a small transmittance of the green LED and the blue LED at the peak position, and the green color filter preferably has a small transmittance of the blue LED and the red LED at the peak position, and the blue color filter Preferably, the red LED and the green LED have a small transmittance at the peak position. Specifically, these transmittances are preferably 0.1 or less, preferably 0.03 or less, more preferably 0.01 or less. The relationship between the backlight and the color filter is described in, for example, JP-A-2009-192661, and can be referred to.

In addition, it is preferable to use a laser light source in the backlight to enlarge the color reproduction domain. The peak wavelengths of the red, green and blue laser sources are preferably 430-480 nm, 520-550 nm, and 620-660 nm, respectively. The backlight of the laser light source is described in Japanese Laid-Open Patent Publication No. 2009-14892, and can be referred to.

Hereinafter, various members used in the VA liquid crystal display device of the present invention will be described in detail.

1. First phase difference field

In the present invention, the first phase difference region composed of one or two or more retardation layers disposed between the rear side polarizer and the VA type liquid crystal cell satisfies the following formula.

0nm≦Re(590)≦10nm, and ∣Rth(590)∣≦25nm

The first phase difference domain satisfies the following formula,

0nm≦Re(590)≦5nm, and ∣Rth(590)∣≦10nm

It is better to satisfy the following formula.

0nm≦Re(590)≦3nm, and ∣Rth(590)∣≦5nm

The wavelength dispersion of the in-plane hysteresis value Re in the first phase difference region is preferably such that the wavelength is increased to a long wavelength in the visible light region, and so-called reverse dispersion property is exhibited. That is, it is preferable to satisfy Re(450)<Re(550)<(Re(590)<Re(630). The reason is that the center of the visible light field is due to the reverse wavelength dispersion of Re in the first phase difference field. The wavelength is about 550 nm, and if the optical characteristics are optimized, the entire visible light region is preferably optimized. Ideally, the value of Re(λ) divided by the wavelength λ in the first phase difference domain is fixed, and the aspect is fixed. The migration on the Pioncare ball in the visible light field is also independent of the wavelength and can also solve the problem of color shift caused by the oblique direction.

In order to obtain a higher front surface CR, the retardation film constituting the first phase difference region disposed on the rear side has a haze of preferably 0.5 or less, preferably 0.3 or less, more preferably 0.2 or less.

In addition, in this specification, the measuring method of the haze of a film is as follows. A film sample of 40 mm × 80 mm was prepared, and the measurement was carried out in accordance with JIS K-6714 using a haze meter (NDH-2000, manufactured by Nippon Denshoku Industries Co., Ltd.) in an environment of 25 ° C and 60% RH.

The first phase difference field may be composed of one or two or more retardation films. There is no particular limitation on the material system. As the film satisfying the above characteristics, a cellulose-based film and an acrylic polymer film are preferable.

Deuterated cellulose film:

In the present specification, the term "deuterated cellulose-based film" means a film containing deuterated cellulose as a main component (50% by mass or more of the total component). In the deuterated cellulose used in the production of the film, the hydroxyl group-based hydrogen atom of the cellulose is replaced by a mercapto group. The hydroxyl group of the cellulose-deuterated cellulose may be deuterated, and the substituent may be any of an ethylene group having 2 carbon atoms and a carbon number of 22 from a mercapto group. In the deuterated cellulose used in the present invention, the degree of substitution of the hydroxyl group in the cellulose is not particularly limited, and the degree of binding of the substituted hydroxyl group of the cellulose to the hydroxyl group and/or the fatty acid having 3 to 22 carbon atoms is determined. The degree of substitution can be obtained by calculation. The measurement method can be carried out in accordance with ASTM D-817-91.

In addition, as an example of the deuterated cellulose which is a phase difference film material which is a first phase difference phase difference in the present invention, it is described in detail in [0019] to [0025] of JP-A-2006-184640. Deuterated cellulose.

The degree of substitution of the cellulose-degraded cellulose used in the production of the retardation film constituting the first phase difference is not particularly limited, and it is preferable that the degree of substitution of the thiol group of the cellulose is 2.30 to 3.00. Further, in order to obtain a retardation film having a low haze, it is preferable that the thiol substitution degree is low, the thiol substitution degree is preferably 2.30 to 2.65, 2.35 to 2.60 is preferable, and 2.40 to 2.60 is more preferable. On the other hand, in order to show that the retardation film has a reverse wavelength dispersion property, the thiol substitution degree is preferably high, specifically, 2.65 to 3.00 is preferable, 2.75 to 3.00 is preferable, and 2.80 to 3.00 is more preferable.

Further, in the case where the mercapto substituent of the above-described deuterated cellulose is substantially composed of at least two types of an ethyl fluorenyl group, a fluorenyl group and a butyl group, the total degree of substitution is known to be 2.30 to 3.00. The optical anisotropy of the deuterated cellulose-based film can be effectively reduced. The preferred thiol substitution degree is 2.35 to 3.00, and more preferably 2.40 to 3.00.

Further, the degree of polymerization of the cellulose-degraded cellulose used for the production of the retardation film in the first phase difference region is preferably 180 to 700, and the cellulose acetate is preferably 180 to 550. 180~400 is better, 180~350 is especially good. When the degree of polymerization is too high, the viscosity of the deuterated cellulose in the coating solution becomes too high, and it becomes difficult to produce the film by casting. When the degree of polymerization is too low, the strength of the produced film is lowered. In addition, the average degree of polymerization can be measured according to the limit viscosity method of Uda et al. (Uda Kazuo, Saito Hideo, Ai Wei Society, Vol. 18, No. 1, pp. 105-120, 1962). It is described in detail in JP-A-9-95538.

Further, the molecular weight distribution of the deuterated cellulose used in the production of the retardation film in the first phase difference region is evaluated by gel permeation chromatography, and the polydispersity index Mw/Mn (Mw is mass) The average molecular weight, Mn is a number average molecular weight), and the molecular weight distribution is narrow. As a specific value of Mw/Mn, 1.0 to 3.0 is preferred, 1.0 to 2.0 is more preferred, and 1.0 to 1.6 is preferred.

In order to produce a film in which one sheet or other film satisfies the optical characteristics required in the first phase difference, the deuterated cellulose and various additives can be used at the same time. Examples of the usable additive include a compound which reduces optical anisotropy, a wavelength dispersion adjuster, an ultraviolet preventive agent, a plasticizer, a deterioration preventive agent, fine particles, an optical property adjuster, and the like. Examples of the additives which can be used in the present invention include various additives described in detail in [0026] to [0218] of JP-A-2006-184640. Further, the preferred range of the added amount is also the same as the preferred range described in the column.

The compound which lowers the optical anisotropy may or may not contain an aromatic group. Further, the compound having a reduced optical anisotropy is preferably a molecular weight of 150 or more and 3,000 or less, more preferably 170 or more and 2,000 or less, and particularly preferably 200 or more and 1,000 or less. In the range of these molecular weights, it may be a specific monomer structure, or an oligomer structure or a polymer structure in which a plurality of monomer units are combined.

The compound which lowers the optical anisotropy is preferably a solid at 25 ° C or a solid having a melting point of 25 to 250 ° C, more preferably a solid at 25 ° C or a solid having a melting point of 25 to 200 ° C. Further, it is preferred that the compound having a reduced optical anisotropy is not volatilized during the casting and drying of the coating liquid produced by the deuterated cellulose-based film.

The amount of the compound which lowers the optical anisotropy is preferably 0.01 to 30% by mass based on the solid content of the deuterated cellulose, preferably 1 to 25% by mass, and particularly preferably 5 to 20% by mass. In particular, in the present invention, it is preferable to add at least one compound having a reduced thiol substitution degree of 2.85 to 3.00 to the above-mentioned added amount to lower the optical anisotropy.

Further, the compound which lowers the optical anisotropy may be used singly or in combination of two or more kinds of compounds. Further, the period of addition of the compound which lowers the optical anisotropy may be added to the solution forming method at any timing in the coating liquid preparation step or at the end of the coating liquid preparation step.

In the present invention, the deuterated cellulose-based film used as one or all of the first phase difference domains is preferably produced by a solution casting method. In this method, a solution (coating liquid) in which deuterated cellulose is dissolved in an organic solvent can be used to produce a film. In the case of using the above additives, the additives can be added at any timing of the coating liquid preparation. For the method for producing the cellulose-based film which can be used in the present invention, the descriptions of [0219] to [0224] of JP-A-2006-184640 can be referred to.

A layer casting method such as a co-casting method, a sequential casting method, or a coating method may be used as the above-described solution casting method. In the case of production by the co-casting method and the sequential casting method, first, a deuterated cellulose solution (coating liquid) for each layer is prepared. The co-casting method (multi-layer simultaneous casting) is performed on a casting support (belt or drum), and each of the layers (which may be three or more) is simultaneously extruded from another slit or the like. The coating liquid is extruded by a nozzle for casting with a coating liquid, and each layer is simultaneously cast, peeled off from the support at an appropriate timing, and dried to form a film casting method.

In the successive casting method, the coating liquid for casting of the first layer is extruded and cast from the casting nozzle first, and dried or not dried, and the nozzle is self-casting. The coating liquid for casting for the second layer is the main point of casting, and if necessary, the coating liquid can be successively cast to the third layer or more, and the support is peeled off and dried at an appropriate period to form a film flow. Yanfa.

In general, in the coating method, a film of a core layer is formed into a film by a solution film forming method, and a coating liquid applied to a surface layer is prepared, and coated on each side or both surfaces by a suitable coater. The dried coating liquid is formed into a film. A method of forming a film of a laminated structure.

Acrylic polymer film:

The acrylic polymer film is a film having an acrylic polymer having a repeating unit induced by at least one of (meth) acrylate as a main component. Preferred examples of the acrylic polymer film include a repeating unit induced by (meth) acrylate, and at least one unit selected from a lactone ring unit, a maleic anhydride unit, and a glutaric anhydride unit. Acrylic polymer. This acrylic polymer is described in detail in JP-A-2008-9378, and can be referred to.

As a method of forming a film, various film forming methods can be used, and examples thereof include a solution casting method (solution casting method), a melt extrusion method, a calendering method, and a compression molding method. Among these film forming methods, a solution casting method (solution casting method) or a melt extrusion method is particularly preferred.

Examples of the solvent used in the solution casting method (solution casting method) include a chlorine-based solvent such as chloroform or dichloromethane; an aromatic solvent such as toluene, xylene or benzene; methanol, ethanol, and isopropyl alcohol; An alcohol-based solvent such as alcohol, n-butanol or 2-butanol; methyl cellosolve, ethyl cellosolve, butyl cellosolve, dimethylformamide, dimethyl hydrazine, dioxane, cyclohexane Ketone, tetrahydrofuran, acetone, methyl ethyl ketone, ethyl acetate, diethyl ether and the like. These solvents may be used singly or in combination of two or more.

Examples of the apparatus for performing the solution casting method (solution casting method) include a drum type casting machine, a belt type casting machine, and a rotary coater.

Examples of the melt extrusion method include a T die method, a blow molding method, and the like. In this case, the film forming temperature is preferably 150 to 350 ° C, more preferably 200 to 300 ° C.

Further, the thickness of the retardation film which is disposed in the first phase difference region disposed on the rear side is preferably as thin as possible, but in order to suppress corner unevenness, it is necessary to reduce the phase difference due to stress falling on the retardation film. The film is deformed. The film thickness of the retardation film constituting the first phase difference region is preferably 20 μm or more and 200 μm or less from the viewpoint of suppressing corner unevenness and manufacturing suitability.

2. Second phase difference field

In the second phase difference region disposed between the front side polarizer and the liquid crystal cell, it is preferable to adjust the optical characteristics to help improve the contrast in the oblique direction and to reduce the color shift in the black display. One example of a preferred second phase difference is in the range of phase difference of 30 nm ≦ Re (590) ≦ 90 nm and 170 nm ≦ Rth (590) ≦ 300 nm. When it is in this range, the light leakage of the general VA type liquid crystal cell (Δnd (590) is about 180 to 350 nm) in the oblique direction at the time of black display can be alleviated.

Further, as described above, the hysteresis value in the second phase difference domain, particularly the preferred range of Rth, varies depending on the value of Δnd (λ) of the liquid crystal layer. Here, when Rth in the first phase difference region of the wavelength λ is Rth ₁ (λ) and Rth in the second phase difference region is Rth ₂ (λ), Δnd (λ) and the first phase of the liquid crystal layer are obtained. One of the fields of Rth(λ), preferably the second phase difference, in the difference domain satisfies the phase difference field of Δnd(590)-70≦Rth ₁ (590)+Rth ₂ (590)≦Δnd(590)-10, More preferably, it satisfies the phase difference range of Δnd(590)-60≦Rth ₁ (590)+Rth ₂ (590)≦Δnd(590)-20. When it is in this range, the light leakage of the VA type liquid crystal cell in the oblique direction at the time of black display can be further alleviated.

Further, as described above, in order to increase the transmittance at the time of white display (=increasing the front surface CR), the Δnd (590) of the liquid crystal layer is preferably 280 nm or more and 340 nm or less. In this case, the second phase difference field disposed on the front side is

220nm≦Rth(590)≦280nm

Better,

230nm≦Rth(590)≦280nm

For better.

On the other hand, in consideration of manufacturing suitability, it is preferable to use a configuration of a retardation film of Rth (590) ≦ 230 nm as the second phase difference field. In general, in order to obtain a retardation film having a high phase difference, it is necessary to carry out a stretching treatment with a high stretching ratio or to increase an amount of an additive which contributes to a phase difference, but when the stretching ratio is increased, the film is likely to be cut. Further, when the amount of the additive added is increased, the additive may be oozing out from the film.

In order to utilize a retardation film of Rth(590) ≦ 230 nm, Δnd (590) of the liquid crystal cell is preferably Δnd (590) ≦ 290 nm, and Δnd (590) ≦ 280 nm is more preferable.

The second phase difference field may be composed of one retardation film or a laminate of two or more films. Further, the material is not particularly limited insofar as it satisfies the above characteristics. As the various polymer films, for example, a polyester-based polymer such as deuterated cellulose, a polycarbonate-based polymer, polyethylene terephthalate or polyethylene naphthalate, or polymethyl methacrylate can be used. An acrylic polymer such as an ester, a styrene polymer such as polystyrene or acrylonitrile ‧ styrene copolymer (AS resin), or the like. Further, a polyamide polymer such as polyethylene or polypropylene, a polyolefin polymer such as an ethylene/propylene copolymer, a vinyl chloride polymer, a nylon or an aromatic polyamide, or the like can be used. , a quinone imine polymer, a fluorene polymer, a polyether fluorene polymer, a polyether ether ketone polymer, a polyphenylene sulfide polymer, a vinylidene chloride polymer, a vinyl alcohol polymer, One or two or more polymers selected from the group consisting of a vinyl butyral polymer, an aryl ester polymer, a polyoxymethylene polymer, an epoxy polymer, and a polymer in which the polymer is mixed are mainly used. The component is formed into a polymer film to satisfy a combination of the above characteristics, and is used for producing a retardation film having a second phase difference.

As the retardation film constituting the second phase difference field, a deuterated cellulose-based film can be preferably used. The raw material of the deuterated cellulose-based film constituting the retardation film in the second phase difference field is preferably a thiol substitution degree of 2.00 to 3.00. Further, the film may be stretched to adjust to a desired hysteresis value, but from the viewpoint of the hysteresis value at the time of extension, the thiol substitution degree is preferably low. However, the lower the degree of substitution of the thiol group, the higher the Rth of the film when it is not extended. Therefore, the retardation film of the VA liquid crystal display device preferably has a thiol substitution degree of 2.00 to 2.65, and 2.20 to 2.65. For better, 2.30~2.60 is better. On the other hand, in order to make the retardation film exhibit reverse wavelength dispersion, the thiol substitution degree is preferably high, specifically, 2.65 to 3.00 is preferable, 2.75 to 3.00 is preferable, and 2.80 to 3.00 is more preferable.

Further, the cellulose deuterated cellulose is preferably cellulose acetate, and may be substituted with an ethyl hydrazine group or may be substituted with a fluorenyl group other than an ethyl fluorenyl group or an ethyl fluorenyl group. Wherein, it is preferably a deuterated cellulose having at least one mercapto group selected from an ethyl group, a propyl group and a butyl group, and more preferably having at least two selected from the group consisting of an ethyl group, a propyl group and a butyl group. Sulfhydryl cellulose. Furthermore, it is preferred to use a cellulose fluorinated group having an ethyl fluorenyl group, a propyl fluorenyl group and/or a butyl fluorenyl group. More preferably, the degree of substitution of the acetyl group is 1.0 to 2.97, and the degree of substitution of the propyl fluorenyl group and/or the butyl fluorenyl group is 0.2 to 2.5 deuterated cellulose.

Further, the above-mentioned deuterated cellulose has a mass average degree of polymerization of from 200 to 800, more preferably from 250 to 550. Further, the deuterated cellulose used in the present invention has a number average molecular weight of 70,000 to 230,000, preferably a number average molecular weight of 75,000 to 230,000, more preferably a number average molecular weight of 78,000 to 120,000.

In the same manner as the raw material of the deuterated cellulose which is used as the retardation film in the first phase difference field, the compound which reduces the optical anisotropy or the like is used as the phase difference film in the first phase difference region. The additive used for the production of the deuterated cellulose-based film is preferably used in the production of a deuterated cellulose-based film for a retardation film in the second phase difference region. On the other hand, in the production of a deuterated cellulose-based film for a retardation film in the second phase difference region, it is preferable to use a hysteresis value expression agent as an additive. Examples of the hysteresis value expression agent that can be used include those of a rod-shaped or disk-shaped compound and a positive birefringence compound. As the rod-like or disk-like compound, a compound having at least two kinds of aromatic rings can be preferably used as a hysteresis value expression agent. The amount of the hysteresis value expression agent composed of the rod-like compound is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 20 parts by mass, per 100 parts by mass of the polymer component containing cellulose deuterated. . The disk-shaped hysteresis value expression agent is preferably used in an amount of 0.05 to 20 parts by mass, and preferably 0.1 to 15 parts by mass, based on 100 parts by mass of the above-mentioned deuterated cellulose resin. It is preferably used in the range of 0.1 to 10 parts by mass.

Since the disk-shaped compound is superior to the rod-like compound in terms of the Rth hysteresis value, it is preferably used in the case where the extra large Rth hysteresis value is necessary. Two or more types of hysteresis value expression agents can also be used.

The hysteresis value agent preferably has a maximum absorption value in the wavelength range of 250 to 400 nm, and substantially no absorption value in the visible light field.

(1) Discotic compound

The discotic compound will be described. As the discotic compound, a compound having at least one aromatic ring can be used.

In the present specification, the "aromatic ring" includes an aromatic heterocyclic ring in addition to the aromatic hydrocarbon ring. The compound of the above-mentioned disk-shaped compound which can be used in the present invention is, for example, a compound of [0038] to [0046] described in JP-A-2008-181105.

The example of the above-mentioned discotic compound which can be used for the production of the retardation film in the second phase difference region contains the compound represented by the following general formula (I).

Wherein X ¹ is a single bond, -NR ⁴ -, -O- or S-; X ² is a single bond, -NR ⁵ -, -O- or S-; X ³ is a single bond, -NR ⁶ -, -O- or S-. Further, each of R ¹ , R ² and R ³ is independently an alkyl group, an alkenyl group, an aromatic ring group or a heterocyclic group: R ⁴ , R ⁵ and R ⁶ are each independently a hydrogen atom, an alkyl group or an alkenyl group. , aryl or heterocyclic group.

Hereinafter, preferred examples (I-(1) to IV-(10)) of the compound represented by the above general formula (I) are shown below, but the present invention is not limited to these specific examples.

(2) rod-like compounds

In the present invention, in addition to the above-described discotic compound, a rod-like compound having a linear molecular structure may be suitably used. The above-mentioned rod-like compound which can be used in the present invention is, for example, a compound of [0053] to [0095] described in JP-A-2007-268898.

(3) Positive birefringent compound

The term "positive birefringent compound" refers to a polymer in which the refractive index of light in the alignment direction is greater than the refractive index of light orthogonal to the alignment direction when light is incident on a layer formed by uniaxial alignment of molecules. .

The positive birefringent compound is not particularly limited, and examples thereof include an intrinsic double of polyamine, polyimide, polyester, polyether ketone, polyamidoximine, and polyester quinone. The polymer having a positive refractive index is preferably a polyether ketone or a polyester polymer, and more preferably a polyester polymer.

The polyester-based polymer is a mixture of an aliphatic dicarboxylic acid having 2 to 20 carbon atoms and an aromatic dicarboxylic acid having 8 to 20 carbon atoms, and an aliphatic diol having a carbon number of 2 to 12 and a carbon number. a reaction of at least one type of diol selected from 4 to 20 alkyl ether diols and 6 to 20 carbon aromatic diols, and the reactants at both ends are directly or in combination with the reactants The reaction of a monocarboxylic acid or a monohydric alcohol or a phenol can also carry out so-called terminal blocking. This terminal blocking is carried out because it does not contain a free carboxylic acid in particular, and it is effective from the point of storage property, etc.. The dicarboxylic acid using the polyester polymer of the present invention is preferably an aliphatic dicarboxylic acid residue having 4 to 20 carbon atoms or an aromatic dicarboxylic acid residue having 8 to 20 carbon atoms.

Examples of the aliphatic dicarboxylic acid having 2 to 20 carbon atoms which are preferably used include oxalic acid, malonic acid, succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, and pimelic acid. Suberic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid.

Further, the aromatic dicarboxylic acid having 8 to 20 carbon atoms is phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalene dicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1, 8-naphthalenedicarboxylic acid, 2,8-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and the like.

Among these, preferred aliphatic dicarboxylic acids are malonic acid, succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, sebacic acid, and 1,4-cyclohexane. The dicarboxylic acid is an aromatic dicarboxylic acid such as phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalene dicarboxylic acid or 1,4-naphthalenedicarboxylic acid. The particularly preferred aliphatic dicarboxylic acid component is succinic acid, glutaric acid, adipic acid, and the aromatic dicarboxylic acid is phthalic acid, terephthalic acid, and isophthalic acid.

At least one of the above-mentioned aliphatic dicarboxylic acid and aromatic dicarboxylic acid, or a combination thereof, may be used in combination without particular limitation, and there is no problem in combining several kinds of components.

The diol or aromatic ring used in the above-mentioned positive birefringent compound contains a diol, and may be, for example, an aliphatic diol having 2 to 20 carbon atoms, an alkyl ether diol having 4 to 20 carbon atoms, and a carbon number of 6~. The aromatic ring of 20 contains the diol selected.

Examples of the aliphatic diol having 2 to 20 carbon atoms include alkyl diols and alicyclic diols, such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, and 1,2-butane. Alcohol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dihydroxymethylpentane), 2-n-butyl-2-ethyl-1,3-propanediol ( 3,3-dimethylol heptane), 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol , 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-18 These alcohols may be used alone or in combination of two or more kinds.

Preferred aliphatic diols are ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3. -propylene glycol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanediol, 1 , 4-cyclohexanedimethanol, particularly good ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butane Alcohol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol.

As the alkyl ether glycol having 4 to 20 carbon atoms, for example, polytetramethylene ether glycol, polyvinyl ether glycol, and polypropylene ether glycol are preferable, and a combination thereof. The average degree of polymerization is not particularly limited, and is preferably 2 to 20, preferably 2 to 10, more preferably 2 to 5, and particularly preferably 2 to 4. As such examples, for example, Carbowax resin, Pluronics resin, and Niax resin are used as representative and commercially available polyether diols. class.

The aromatic diol having 6 to 20 carbon atoms is not particularly limited, and examples thereof include bisphenol A, 1,2-hydroxybenzene, 1,3-hydroxybenzene, 1,4-hydroxybenzene, and 1,4-benzene. Dimethanol is preferably bisphenol A, 1,4-hydroxybenzene or 1,4-benzenedimethanol.

The above-mentioned positive birefringent compound is preferably a compound in which an end is an alkyl group or an aromatic group is blocked. By using a hydrophobic functional group to protect the terminal, it is effective for deterioration over time under high temperature and high humidity, and it is a cause of exhibiting a role of delaying hydrolysis of the ester group.

In order to prevent the both ends of the above-mentioned positive birefringent compound from being a carboxylic acid or an OH group, it is preferably protected with a monohydric alcohol residue or a monocarboxylic acid residue.

In this case, the monohydric alcohol is preferably a substituted or unsubstituted monohydric alcohol having 1 to 30 carbon atoms, and examples thereof include methanol, ethanol, propanol, isopropanol, butanol, isobutanol, and pentanol. Pentanol, hexanol, isohexanol, cyclohexanol, octanol, isooctanol, 2-ethylhexanol, decyl alcohol, isodecyl alcohol, third sterol, decyl alcohol, dodecanol, dodecane An aliphatic alcohol such as hexanol, dodecyl octanol, allyl alcohol or oleyl alcohol, a substituted alcohol such as benzyl alcohol or 3-phenylpropanol, or the like.

Preferred end-blocking alcohols are methanol, ethanol, propanol, isopropanol, butanol, isobutanol, isoamyl alcohol, hexanol, isohexanol, cyclohexanol, isooctanol, 2-ethyl P-hexanol, isodecyl alcohol, oleyl alcohol, benzyl alcohol, particularly preferred are methanol, ethanol, propanol, isobutanol, cyclohexanol, 2-ethylhexanol, isodecyl alcohol, benzyl alcohol.

Further, in the case of blocking with a monocarboxylic acid residue, the monocarboxylic acid used as the monocarboxylic acid residue is preferably a substituted or unsubstituted monocarboxylic acid having 1 to 30 carbon atoms. These may be aliphatic monocarboxylic acids or carboxylic acids containing aromatic rings. When a preferred aliphatic monocarboxylic acid is described, acetic acid, propionic acid, butyric acid, caprylic acid, caproic acid, capric acid, dodecanoic acid, stearic acid, or oleic acid may be mentioned as a single ring containing an aromatic ring. The carboxylic acid is, for example, benzoic acid, p-t-butyl benzoic acid, p-third amyl benzoic acid, phenylacetic acid, m-phenylacetic acid, p-phenylacetic acid, dimethyl benzoic acid, ethyl benzoic acid, The propyl benzoic acid, the amino benzoic acid, the ethoxylated benzoic acid, and the like may be used alone or in combination of two or more.

The synthesis of the above-mentioned positive birefringent compound can be carried out by a conventional method to heat-condense or transesterify the above dicarboxylic acid with a diol or/or a terminally blocked monocarboxylic acid or a monohydric alcohol. It is legally or simply synthesized by any of the methods of interfacial condensation of hydrazine and diol with such an acid. The polyester-based additives are described in detail in the "Inners' Theory and Application" (fortunately, the research and application of Kasuga Co., Ltd., the first edition of the first edition of March 1, 2008). In addition, it is also possible to use the special Kaikai 05-155809, the special Kaiping 05-155810, the special Kaikai 5-117073, the special opening 2006-259494, the special Kaiping 07-330670, the special opening 2006-342227, the special opening 2007 Material described in each of the publications of -003679.

Specific examples of the above-mentioned positive birefringence compound are described below, but the positive birefringence compound which can be used in the present invention is not limited thereto.

In Tables 1 and 2, PA represents phthalic acid, TPA represents terephthalic acid, IPA represents isophthalic acid, AA represents adipic acid, SA represents succinic acid, and 2,6-NPA represents 2,6-naphthalenedicarboxylic acid, 2,8-NPA represents 2,8-naphthalene dicarboxylic acid, respectively, 1,5-NPA represents 1,5-naphthalene dicarboxylic acid, respectively, and 1,4-NPA represents 1, respectively. 4-Naphthalene dicarboxylic acid, 1,8-NPA means 1,8-naphthalene dicarboxylic acid, respectively.

The amount of the above-mentioned positively birefringent compound to be added is preferably 1 to 30 parts by mass, more preferably 4 to 25 parts by mass, and 10 to 20 parts by mass per 100 parts by mass of the deuterated cellulose resin. Very good.

The deuterated cellulose solution used in the production of the above-described deuterated cellulose-based film may have other additives in addition to the hysteresis value expression agent. Examples of other additives include an antioxidant, an ultraviolet absorber, a peeling accelerator, a plasticizer, and the like, and any of them can be used as a known additive.

In order to improve the mechanical properties of the obtained film or to increase the drying speed, a plasticizer may be added to the aforementioned cellulose oxide solution. The compound described in [0067] of JP-A-2008-181105 is exemplified as the above-mentioned plasticizer which can be used in the present invention.

Further, as the retardation film constituting the second phase difference field, a cyclic olefin polymer film is preferably used. The raw material of the cyclic olefin-based polymer film, the method for producing the same, and the method for producing the film using the raw material are described in detail in [0098] to [0193] of JP-A-2006-293342, The invention can be referred to. In the example of the cyclic olefin-based polymer film which can be used as the retardation film in the second phase difference field, For the olefin-based polymer film, commercially available polymers, such as ARTON (manufactured by JSR) and ZERONOR (manufactured by ZEON, Japan), can be used.

Various polymer films used as the retardation film constituting the second phase difference field can be produced by various methods. For example, a solution casting method (solution casting method), a melt extrusion method, a calendering method, a compression molding method, and the like can be given. Among these film forming methods, a solution casting method (solution casting method) or a melt extrusion method is particularly preferred. Moreover, the various polymer film which is a retardation film which comprises a 2nd phase difference field can be the film manufactured by the extension process after shaping|molding. The extension of the film may be a 1-axis extension or a 2-axis extension. Preferably, the two-axis extension process is performed simultaneously or sequentially. In order to achieve large optical anisotropy, it is necessary to stretch the film with a high stretch ratio. For example, it is preferred to extend in the width direction of the film and in the longitudinal direction (flow direction) of the film. The stretching ratio is preferably about 3 to 100%. The extension processing can be carried out using a tenter. Alternatively, it is also possible to extend longitudinally between the rolls.

A layer casting method such as a co-casting method, a sequential casting method, or a coating method may be used as the above-described solution casting method. In the case of production by the co-casting method and the sequential casting method, first, a deuterated cellulose solution (coating liquid) for each layer is prepared. The co-casting method (multi-layer simultaneous casting) is performed on a casting support (belt or drum), and each of the layers (which may be three or more) is simultaneously extruded from another slit or the like. The coating liquid is extruded by a nozzle for casting with a coating liquid, and each layer is simultaneously cast, peeled off from the support at an appropriate timing, and dried to form a film casting method.

In the successive casting method, the coating liquid for casting of the first layer is extruded and cast from the casting nozzle first, and dried or not dried, and the nozzle is self-casting. The coating liquid for casting for the second layer is the main point of casting, and if necessary, the coating liquid can be successively cast to the third layer or more, and the support is peeled off and dried at an appropriate period to form a film flow. Yanfa.

In general, in the coating method, a film of a core layer is formed into a film by a solution film forming method, and a coating liquid applied to a surface layer is prepared, and a coating machine is applied to each side or both surfaces by a suitable coater to form a film. A method of forming a film of a laminated structure.

Further, the retardation film constituting the second phase difference region may be a layer formed by fixing the alignment state after the liquid crystal composition is formed into a desired alignment state, or may have both the layer and the polymerization supporting the layer. a laminate of a film of matter. In the latter aspect, the polymer film can also be utilized as a protective film for a polarizer. In the example of the liquid crystal which can be used for the production of the retardation film in the second phase difference region, various liquid crystals such as a rod-like liquid crystal, a discotic liquid crystal, and a cholesteric liquid crystal are included.

In order to obtain a higher front surface CR, the retardation film constituting the second phase difference region disposed on the front side preferably has a haze of 0.5 or less, preferably 0.3 or less, more preferably 0.2 or less.

In order to suppress corner unevenness, it is necessary to reduce the phase difference film deformation due to the stress falling on the retardation film. The film thickness of the retardation film constituting the second phase difference region disposed on the front side is preferably 20 μm or more and 200 μm or less from the viewpoint of suppressing corner unevenness and manufacturing suitability.

3. Polarizer

The polarizing sub-systems disposed on the front side and the rear side are not particularly limited. A linear polarizing film which is generally used can be used. The linear polarizing film is preferably a coating type polarizing film typified by Optiva Inc. or a polarizing film composed of a binder and iodine or a dichroic dye. The iodine and the dichroic dye in the linear polarizing film are aligned in the binder to find polarizing properties. Preferably, the iodine and the dichroic dye are aligned along the binder molecule or are aligned in a single direction by self-organizing the dichroic dye such as a liquid crystal. Commercially available polarizers are generally prepared by immersing an extended polymer in a bath in a solution of iodine or a dichroic dye, and impregnating the binder with iodine or a dichroic dye in a binder. .

4. Protective film

It is preferable to bond the protective film on both sides of the front side polarizer and the rear side polarizer. However, as shown in FIG. 1, the first and second phase difference fields are composed of one film, and in the case where the film also functions as a protective film, the surface of the liquid crystal cell can be polarized. The protective film is omitted. In a state in which a protective film and one or more retardation films are disposed between the rear side polarizer and the liquid crystal cell, the protective film and one or more retardation films are provided as a laminate, and are satisfied with the first phase. The optical properties required in the field of difference. The preferred material of the protective film is the same as that of the preferred material constituting the retardation film in the first phase difference field.

In the aspect in which a protective film and one or more retardation films are disposed between the front side polarizer and the liquid crystal cell, the protective film and one or more retardation films are preferably used as the laminate, and are satisfied with the second. Optical properties required in the field of phase difference. The protective film has a function of contributing to the improvement of the diagonal direction and the color shift of the black display together with one or more retardation films, that is, it is also possible to display a certain degree of phase difference between Re and Rth. film.

The protective film system disposed on the outer side of the front side polarizer and the rear side polarizer is not particularly limited. A variety of polymer films can be used. It can be the same as the example of the phase difference film which comprises the said 1st phase difference field. For example, a cellulose (for example, a film of cellulose acetate, cellulose propionate, cellulose butyrate, etc.) or a polyolefin (for example, a film) may be mentioned. The olefin polymer, polypropylene), poly(meth)acrylate (for example, polymethyl methacrylate), polycarbonate, polyester, or a film mainly composed of polyfluorene, etc., are not limited thereto. It is also possible to use a commercially available polymer film ("TD80UL" (made by Fujifilm Co., Ltd.) in the case of deuterated cellulose. The olefin polymer is ARTON (made by JSR), ZEONOR (made by Japan ZEON), and the like.

Example

Hereinafter, the examples are given to further illustrate the present invention. The materials, reagents, masses, ratios, operations, and the like shown in the following examples can be appropriately changed without departing from the scope of the main contents of the present invention. Therefore, the scope of the invention is not limited to the specific examples below.

1. Production of film 1~6

The deuterated cellulose having different types of mercapto groups and different degrees of substitution described in the following table was prepared. This was added with sulfuric acid (7.8 parts by mass based on 100 parts by mass of cellulose) as a catalyst, and a carboxylic acid which is a mercapto substituent raw material was added and subjected to a deuteration reaction at 40 °C. At this time, the type and amount of the carboxylic acid are adjusted to adjust the type and degree of substitution of the thiol group. Further, after mashing, aging was carried out at 40 °C. Further, the low molecular weight component of the deuterated cellulose was removed by washing with acetone. Further, the term "Ac" in the table means an ethyl group, and the so-called CTA means a cellulose triacetate (a cellulose ester derivative in which a mercapto group is composed only of an acetate group).

(deuterated cellulose solution)

The following composition was placed in a mixing tank, and each component was stirred and dissolved, and further heated at 90 ° C for about 10 minutes, and then filtered with a filter paper having an average pore diameter of 34 μm and a calcined metal filter having an average pore diameter of 10 μm.

(matting agent dispersion)

Next, the following composition containing the deuterated cellulose solution prepared in the above method was placed in a disperser to prepare a matting agent dispersion.

(additive solution)

Next, the following composition containing the deuterated cellulose solution prepared in the above method was placed in a mixing tank, and stirred and dissolved while heating to prepare an additive solution.

100 parts by mass of the above-described deuterated cellulose solution, 1.35 parts by mass of the matting agent dispersion liquid, and an additive solution in which the hysteresis value agent (1) is added in an amount of 10 parts by mass in the deuterated cellulose-based film. The coating liquid for film formation is prepared. The addition ratio of the additive is a part by mass when the amount of the deuterated cellulose is taken as 100 parts by mass.

The cotton and additives described in the following table were changed to prepare the above solution and dispersion.

Here, the abbreviations of the additive and the plasticizer described in the following table are as follows.

CTA: triacetyl cellulose

TPP: triphenyl phosphate

BDP: biphenyl diphenyl phosphate

Hysteresis value agent (1)

The above coating liquid was cast using a belt casting machine. The film peeled off from the belt using the amount of residual solvent described in the following table is stretched in the longitudinal direction by the stretching ratio described in the following table in the section which is peeled off to the tenter, and then the tenter is used, and the following The stretching ratio described in the above table extends in the width direction, and after stretching in the transverse direction, the film is shrunk (relaxed) in the width direction at a magnification described in the following table, and then the film is detached from the tenter to form a film. Deuterated cellulose film. The residual solvent amount of the film when the tenter is off is as described in the following table. The both end portions were cut before the winding portion to take up a roll film having a width of 2000 mm and a length of 4000 m. The stretching ratio is shown in the following table. With respect to the produced deuterated cellulose-based film, the Re hysteresis value and the Rth hysteresis value at 60 ° RH at 25 ° C and at a wavelength of 590 nm were measured. The results herein are shown in the following table. Further, the average refractive index was taken as 1.48 to calculate Rth(λ).

2. Production of film 7

A retardation film 7 of Re (590) 77 nm and Rth (590) 47 nm was obtained in the same manner as in the optical compensation layer A described in Example 2 of JP-A-2003-315556.

3. Production of film 8

A Z-TAC film (manufactured by Fujifilm Co., Ltd., Re(590) = 1 nm, and Rth (590) = -1 nm) was prepared. In addition, a retardation film 8a of Re (590) 1.5 nm and Rth (590) 207 nm was obtained in the same manner as in the optical compensation layer B described in Example 2 of JP-A-2003-315556. The retardation film 8a is bonded to the surface of the Z-TAC to form a laminated film, and is used as the film 8.

4. Production of film 9

The following composition was placed in a mixing tank, and while stirring, the components were dissolved to prepare a deuterated cellulose solution C.

<醯化cellulose solution C composition>

100 parts by mass of cellulose acetate with a degree of substitution of 2.86

Dichloromethane (1st solvent) 300 parts by mass

Methanol (second solvent) 54 parts by mass

1-butanol 11 parts by mass

The following composition was placed in another mixing tank, and while stirring, the components were dissolved while heating to prepare an additive solution D.

<Additive Solution D Composition>

Methylene chloride 80 parts by mass

Methanol 20 parts by mass

The following optical anisotropy reducing agent A-7 40 parts by mass

Optical anisotropy reducer A-7

40 parts by mass of the additive solution D was added to 465 parts by mass of the deuterated cellulose solution C to prepare a coating liquid. The transparency of the coating solution is preferably 85% or more.

This coating liquid was cast on a support to prepare a deuterated cellulose-based film having a thickness of 80 μm. This was used as the film 9.

5. Production of film 10

The stretched film (protective film A) was produced in accordance with the description of [0223] to [0226] of JP-A-2007-127893. On the surface of the protective film A, the easy-adhesion layer coating composition P-2 is prepared according to the method described in [0232] of the same publication, and the composition is applied to the above according to the method described in [0246] of the same publication. The surface of the film is stretched to form an easy adhesion layer. This film was used as the film 10.

6. Preparation of film 11

A commercially available triacetonitrile cellulose film "TF80UL" (manufactured by Fujifilm) was prepared as a film 1L.

7. Preparation of film 12~16

(modulation of polymer solution)

1) Deuterated cellulose

From the following deuterated celluloses A and B, those selected as shown in the following Table 4 were selected and used. Each of the deuterated celluloses was dried by heating at 120 ° C, and the water content was 0.5% by mass or less, and then 20 parts by mass was used.

‧Deuterated cellulose A:

A powder of cellulose acetate having a degree of substitution of 2.93 was used. The average degree of polymerization of the deuterated cellulose A was 300, and the degree of substitution of the ethyl group of the 6-position was 0.94.

‧Deuterated cellulose B:

A powder of cellulose acetate having a degree of substitution of 2.86 was used. The average degree of polymerization of deuterated cellulose B is 300, the degree of substitution of ethyl sulfonate at position 6 is 0.89, the extraction of acetone is 7% by mass, the ratio of mass average molecular weight/number average molecular weight is 2.3, and the water content is 0.2% by mass. The viscosity in a 6 mass% dichloromethane solution was 305 mPa·s, the residual acetic acid amount was 0.1 mass% or less, the Ca content was 65 ppm, the Mg content was 26 ppm, the iron content was 0.8 ppm, the sulfate ion content was 18 ppm, and the yellow index was 1.9. The amount of free acetic acid was 47 ppm. The powder had an average particle size of 1.5 mm and a standard deviation of 0.5 mm.

2) Solvent

The following solvent A was used. The water content of each solvent is 0.2% by mass or less.

‧Solvent A

Dichloromethane/methanol = 90/10 parts by mass

3) Additives

From the following additives A and B, those described in the following Table 4 were selected and used.

‧Additive A

Cerium oxide microparticles (particle size 20 nm, Mohs hardness of about 7) (0.08 parts by mass)

‧Additive B

Triphenyl phosphate (1.6 parts by mass)

Biphenyl diphenyl phosphate (0.8 parts by mass)

Cerium oxide microparticles (particle size 20 nm, Mohs hardness of about 7) (0.08 parts by mass)

4) Dissolve

Swelling and dissolving were carried out using the dissolution step A described below.

‧Dissolution step A

In the 400 liter stainless steel dissolution tank having a stirring blade and having a cooling water circulation on the outer circumference, the solvent and the additive are charged, and the cellulose hydride is gradually added while stirring and dispersing. After completion of the introduction, the mixture was stirred at room temperature for 2 hours, allowed to swell for 3 hours, and then stirred again to obtain a deuterated cellulose swelling solution.

Further, in terms of stirring, a dissolver type eccentric stirring using a peripheral speed of 15 m/sec (shear stress 5 × 10 ⁴ kgf/m/sec ² [4.9 × 10 ⁵ N/m/sec ² ]) was used. The shaft, and a stirring shaft having an anchor blade at the center axis and stirring at a peripheral speed of 1 m/sec (shear stress: 1 × 10 ⁴ kgf/m/sec ² [9.8 × 10 ⁴ N/m/sec ² ]). The swelling was carried out by stopping the high-speed stirring shaft and having a peripheral speed of the stirring shaft of the anchor blade of 0.5 m/sec.

The swollen solution was heated from a storage tank to a pipe with a sleeve to 50 ° C, and further heated to 90 ° C under a pressure of 2 MPa to be completely dissolved. The heating time is 15 minutes. In this case, the filter, the casing, and the piping which are exposed to a high temperature are made of a Hastelloy alloy and have excellent corrosion resistance, and have a sleeve for allowing the heat medium for heat retention to flow.

Next, the temperature was lowered to 36 ° C to obtain a deuterated cellulose solution.

5) Filter

The obtained deuterated cellulose solution was filtered with a filter paper having an absolute filtration accuracy of 10 μm (#63, manufactured by Toyo Filter Co., Ltd.), and further filtered in a metal calcination filter (FH025, manufactured by Bol Co., Ltd.) having an absolute filtration accuracy of 2.5 μm. A polymer solution was obtained.

(production of film)

The film formation was carried out by the film forming step A described below.

‧ Film forming step A

The deuterated cellulose solution was heated to 30 ° C, and cast through a casting nozzle (described in JP-A-11-314233), and cast onto a mirror-finished stainless steel support having a belt length of 60 m set at 15 °C. The casting speed was 50 m/min and the coating width was 200 cm. The space temperature of the entire casting portion was set at 15 °C. Then, the cellulose-deposited cellulose film which was cast and rotated from the end portion of the casting portion to 50 cm before the peeling was peeled off from the belt, and a dry wind of 45 ° C was blown. Subsequently, it was dried at 110 ° C for 5 minutes and further dried at 140 ° C for 10 minutes to obtain a transparent film of deuterated cellulose.

(extend)

As shown in Table 4 below, the stretching step was carried out by any of the following extension steps A or B.

‧Extension step A

The resulting film was extended using a device having a heating zone between two press rolls. The distance between the press rolls was adjusted so that the aspect ratio (the distance between the press rolls / the substrate inlet width) was 0.1, the substrate temperature before entering the heating zone was 25 ° C, and the heating zone was the temperature described in Table 4 below. . Further, the ratio of the speed of the conveyed pressure feed rolls to the speed of the wound feed rolls was adjusted so as to be adjusted to the stretch ratio described in Table 4 below.

‧Extension step B

After the both ends of the obtained film are held by a tenter clamp, they extend in a direction orthogonal to the conveyance direction in the heating zone. The heating zone was set to the temperature described in the following Table 4, and the stretching ratio calculated from the expansion ratio of the tenter was used as the magnification described in Table 4 below.

Films 12 to 16 were produced as described above. The production conditions are summarized in Table 4 below.

8. Preparation of film 17

In the production of the film 4, the same amount was produced except that the amount of addition of the hysteresis value expression agent (1) was changed to 12 parts by mass, the longitudinal stretching ratio was changed to 20%, and the lateral stretching ratio was changed to 35%.

9. Preparation of film 18

In the production of the film 5, the same procedure was carried out except that the addition amount of the hysteresis value expression agent (1) was changed to 7.2 parts by mass, the longitudinal stretching ratio was changed to 35%, and the lateral stretching ratio was changed to 75%.

10. Production of film 19

Using the solid state power processor 6KVA (PILAR), the market is down. The surface of the olefin polymer film "ZEONORZF14-060" (manufactured by OPTES Co., Ltd.) was subjected to corona discharge treatment. This film was used as the film 19. The film had a thickness of 60 μm.

11. Production of film 20

The surface of a commercially available cycloolefin polymer film "ARTON FLZR50" (manufactured by JSR Co., Ltd.) was subjected to corona discharge treatment in the same manner as in the film 18. This film was used as the film 20. The film had a thickness of 50 μm.

12. Production of film 21

Make the market drop The olefin-based polymer film "ZEONORZF14-100" (manufactured by OPTES Co., Ltd.) was 1.55 times in the MD direction and 1.8 times in the TD direction at a temperature of 142 ° C. After the fixed end biaxial stretching, the solid corona treatment machine 6KVA was used. (PILAR (manufactured by the company)) The surface was subjected to corona discharge treatment. This film was used as the film 21. The film had a thickness of 38 μm.

13. Production of film 22

Preparation of deuterated cellulose propionate ("CAP482-20" (manufactured by Eastman Chemical Co., Ltd.); degree of substitution of ethyl thiol 0.2, degree of substitution of propyl thiol). 8 mass% of 1, 4-phenylene-tetraphenyl phosphate was added thereto as a plasticizer, and 0.5 mass% of IRGANOX-1010 (manufactured by Ciba Specialty Chemicals Co., Ltd.) was used as a deterioration preventing agent (antioxidant) in the drum. Mix the mixer for 30 minutes. The resulting mixture was dried at a hot air temperature of 150 ° C and a dew point of -36 ° C using a dehumidifying hot air dryer (DMZ2). Next, the mixture was supplied to a TECHNOVEL (manufacturing) two-axis extruder, and an AEROSIL (AEROSIL) 200V (as a matting agent) was added from a central portion of the extruder with an opening portion of the additive hopper. 0.016 μm of vermiculite particles, manufactured by AEROSIL Co., Ltd., so as to have an extrusion amount of 0.05%, and added as a UV absorber, TINUVIN 360 (manufactured by Ciba Specialty Chemicals Co., Ltd.) so as to be pressed from the same opening The amount was 0.5% and it was melt extruded. The film thickness of the melt-extruded film was 220 μm.

Further, the film was stretched at a temperature of 142 ° C in a direction of 1.3 times in the MD direction and 2.4 times in the TD direction to form a film. This film was used as the film 22. Further, the film had a film thickness of 70 μm.

14. Production of film 23

In the production of the film 1, a film was produced and used in the same manner as in the production of the film 1 except that the cellulose shown in the following table was used as a raw material and the production conditions were replaced by the following table. As the film 23. In addition, the following additives and plasticizers are abbreviated as described above.

Hysteresis value agent (2)

15. Production of film 24

(modulation of polymer solution)

1) Polymer

A polycarbonate copolymer of bisphenol A and 9,9-bis(4-hydroxy-3-methylphenyl)anthracene is used as a bisphenol component. The polymer was dried by heating to 120 ° C, and after the water content was 0.5% by mass or less, 20 parts by mass was used.

2) Solvent

The following solvent A was used. The water content of each solvent is 0.2% by mass or less.

‧Solvent A

Dichloromethane = 100 parts by mass

3) Additives

The following additive A was used.

‧Additive A

Cerium oxide microparticles (particle size 20 nm, Mohs hardness of about 7) (0.08 parts by mass)

4) Dissolve

The swelling and the dissolution are carried out by the dissolution step A described below.

‧Dissolution step A

In a 400-liter stainless steel dissolution tank having a stirring blade and having a cooling water circulation on the outer circumference, the solvent and the additive are charged, and the polymer is gradually added while stirring and dispersing. After the completion of the reaction, the mixture was stirred at room temperature for 2 hours to obtain a polymer solution.

5) Filter

The obtained polymer solution was filtered through a filter paper (#63, manufactured by Toyo Filter Co., Ltd.) having an absolute filtration accuracy of 10 μm, and further filtered in a metal calcination filter (FH025, manufactured by Bol) which has an absolute filtration accuracy of 2.5 μm. Polymer solution.

(production of film)

Film formation was carried out by the film forming step A described below.

‧ Film forming step A

The polymer solution was heated to 30 ° C, and cast through a casting nozzle (described in JP-A-11-314233), and cast onto a mirror-finished stainless steel support having a belt length of 60 m set at 15 °C. The casting speed was 10 m/min and the coating width was 150 cm. The space temperature of the entire casting portion was set to 15 °C. Then, the cellulose-deposited cellulose film which was cast and rotated from the end portion of the casting portion to 50 cm before the peeling was peeled off from the belt, and a dry wind of 45 ° C was blown. Subsequently, it was dried at 110 ° C for 5 minutes and further dried at 140 ° C for 10 minutes to obtain a transparent polymer film.

(extend)

The extension step A described below was carried out.

‧Extension step A

The resulting film was extended using a device having a heating zone between two press rolls. The distance between the press rolls was adjusted so that the aspect ratio (the distance between the press rolls / the substrate inlet width) was 8, the substrate temperature before entering the heating zone was 25 ° C, and the heating zone was 210 °C. Further, a transparent polymer film having a Re/Rth of 140/72 nm was obtained by maintaining a speed ratio of the speed of the fed nip rolls to the speed of the wound nip rolls.

16. Production of film 25

Synthesis of 2,2'-bis(3,4-dicarboxyphenyl)hexafluoropropane and 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl The quinone imine was dissolved in cyclohexanone to prepare a 15% by mass solution. The polyimine solution was applied onto a biaxially stretched polyester film (substrate), and dried at 120 ° C for 10 minutes to form a non-liquid crystalline polymer layer (optical compensation layer B) having a thickness of 5 μm to obtain a laminate. body.

The laminate and the film 9 produced above were bonded together using an adhesive. The surface of the optical compensation layer B is brought into contact with the surface of the film 9 to be bonded. Then, the substrate is removed to make a film 25.

17. Production of film 26

The following composition was placed in a mixing tank, and each component was dissolved while being superheated, and then filtered using a filter paper having an average pore diameter of 34 μm and a calcined metal filter having an average pore diameter of 10 μm to prepare a cellulose oxide solution.

(deuterated cellulose solution)

100 parts by mass of cellulose acetate with a degree of substitution of 2.81

Hysteresis value agent (1) 8.5 parts by mass

Hysteresis value agent (3) 7.0 parts by mass

Dichloromethane 428.4 parts by mass

Methanol 64.0 parts by mass

The composition of the aforementioned hysteresis value expression agent (3) is shown in Table 6 below. Further, in the following Table 6, EG is represented by ethylene glycol, TPA is represented by terephthalic acid, PA is represented by phthalic acid, AA is represented by adipic acid, and SA is represented by succinic acid. Further, the hysteresis value expression agent (3) is a non-phosphate ester type compound and is a compound having a function as a hysteresis value expression agent. The end of the aforementioned hysteresis value agent (3) is blocked with an ethyl sulfonate group.

The above-described prepared deuterated cellulose solution was rapidly cast onto a belt casting machine. The film having a residual solvent amount of about 30% by mass and having been peeled off from the belt was stretched in the width direction at a stretching ratio of 16% by a tenter at 140 °C. Then, it is transferred from a tenter to a roll transfer, and then dried at 110 ° C to 150 ° C to produce a film 26 . Further, the film had a film thickness of 85 μm.

In the production of the film 26, there is no problem that occurs in the production of the film 1 (the action caused by adhesion to the manufacturing machine during the high-temperature treatment such as the drying step or the like, or adhesion to the film is not preferable. The resulting planar failure).

Since the hysteresis value expression agent (3) used as the hysteresis value expression agent has a function as a plasticizer in the production of the film 26, the conventional method called TPP and BDP used in the production of the film 1 is not used. Low molecular plasticizer.

By using the above-mentioned positive birefringence compound such as the hysteresis value expression agent (3) as described above, since the above-mentioned problem can be solved, the above-mentioned positive birefringence compound is a preferable hysteresis value expression agent from the viewpoint of film production. .

18. Production of film 27

(lower substitution layer with deuterated cellulose solution)

The composition described below was placed in a mixing tank, and while stirring and dissolving each component while superheating, a deuterated cellulose solution for a low substitution layer was prepared.

100 parts by mass of cellulose acetate with a degree of substitution of 2.43

Hysteresis value agent (1) 4.0 parts by mass

Hysteresis value agent (4) 10.0 parts by mass

Methylene chloride 351.5 parts by mass

Methanol 52.5 parts by mass

The composition of the above-mentioned hysteresis value expression agent (4) is shown in Table 7 below. Further, in the following Table 7, EG is represented by ethylene glycol, PG is represented by propylene glycol, BG is represented by butylene glycol, TPA is represented by terephthalic acid, PA is represented by phthalic acid, and AA is represented by adipic acid or SA. Expressed as succinic acid. Further, the hysteresis value expression agent (4) is a non-phosphate ester type compound and has a compound functioning as a hysteresis value. The end of the hysteresis value agent (4) is blocked by an ethyl thiol group.

(Highly substituted layer with deuterated cellulose solution)

The following composition was placed in a mixing tank, and each component was stirred and dissolved to prepare a cellulose oxide solution for a high degree of substitution layer.

Cellulose acetate with a degree of substitution of 2.79 100.0 parts by mass

Hysteresis value agent (4) 11.0 parts by mass

Vermiculite particles having an average particle diameter of 16 nm (Aerosol R972 Japan AEROSIL Co., Ltd.) 0.15 parts by mass

Methylene chloride 395.0 parts by mass

Methanol 59.0 parts by mass

(Production of bismuth cellulose sample)

Each was cast to form a core layer having a thickness of 82 μm from the low-degree-substituted layer using a deuterated cellulose solution, and a skin A layer and a skin B layer having a thickness of 2 μm were formed from the high-substituted layer using a deuterated cellulose solution. The obtained film was peeled off from the belt and clamped on the clamp. When the residual solvent amount was 20% for the mass of the entire film, the tenter was used to extend in the width direction at an extension temperature of 180 ° C. Extend 18%. Then, the clamp was removed from the film and dried at 130 ° C for 20 minutes to prepare a film 27.

19. Production of film 28

In the production of the film 27, the film thickness was changed to 75 μm and the stretching ratio was changed to 20%, and the film 27 was produced in the same manner.

20. Production of film 29

(lower substitution layer with deuterated cellulose solution)

The composition described below was placed in a mixing tank, and while stirring and dissolving each component while superheating, a deuterated cellulose solution for a low substitution layer was prepared.

100 parts by mass of cellulose acetate with a degree of substitution of 2.43

Hysteresis value agent (4) 18.5 parts by mass

Dichloromethane 365.5 parts by mass

Methanol 54.6 parts by mass

(Highly substituted layer with deuterated cellulose solution)

The following composition was placed in a mixing tank, and each component was stirred and dissolved to prepare a cellulose oxide solution for a high degree of substitution layer.

Cellulose acetate with a degree of substitution of 2.79 100.0 parts by mass

Hysteresis value agent (4) 11.0 parts by mass

Vermiculite particles having an average particle diameter of 16 nm (aerosil R972 manufactured by AEROSIL Co., Ltd.) 0.15 parts by mass

Methylene chloride 395.0 parts by mass

Methanol 59.0 parts by mass

(Production of bismuth cellulose sample)

Each was cast to form a core layer having a thickness of 37 μm from the low-degree-substituted layer using a deuterated cellulose solution, and a skin A layer and a skin B layer having a thickness of 2 μm were formed from the high-substituted layer using a deuterated cellulose solution. The obtained film was peeled off from the belt and clamped on the clamp, and when the amount of the remaining solvent was 20% in terms of the mass of the entire film, it was dried at a temperature of 200 ° C for 30 minutes, and then at 130 ° C. It was allowed to dry for 20 minutes to make a film 29.

21. Characteristics of film 1~29

The characteristics of the above films 1 to 29 are summarized in the following table. In addition, Re (590) and Rth (590) of each film were humidity-conditioned at 25 ° C and 60% RH for 2 hours in a sample of 30 mm × 40 mm, and in a KOBRA 21ADH (manufactured by Oji Scientific Instruments Co., Ltd.) at a wavelength of 590 nm. The measurement was calculated for the films 1 to 6, 9, 11 to 18, 22, 23, and 26 to 29, which are assumed to have an average refractive index of 1.48 and a film thickness. In addition, the case of the film other than the film is assumed as the average refractive index, 1.52 for the film 7 and 20, 1.60 for the film 8, 1.50 for the film 10, 1.53 for the film 21, and 1.53 for the film 21, for the film 24. Use 1.59 for the film 25 and 1.58 for the film 25.

22. Production of polarizing plates

A polyvinyl alcohol (PVA) film having a thickness of 80 μm was immersed in an iodine aqueous solution having an iodine concentration of 0.05% by mass for 30 seconds at 30° C. for dyeing, and then immersed in a boric acid aqueous solution having a boric acid concentration of 4% by mass for 60 seconds. After extending longitudinally five times its original length, it was dried at 50 ° C for 4 minutes to obtain a polarizing film having a thickness of 20 μm.

Among the films 1 to 29 shown in the above table, the deuterated cellulose-based film was subjected to a saponification treatment as follows. After immersing each film in an aqueous sodium hydroxide solution of 1.5 mol/liter and 55 ° C, the sodium hydroxide was sufficiently washed with water. Then, after immersing in a 0.005 m/liter and 35 ° C dilute sulfuric acid aqueous solution for 1 minute, it was immersed in water and the dilute sulfuric acid aqueous solution was sufficiently washed. Finally, the sample was sufficiently dried at 120 °C.

The polarizing film was sandwiched between any two of the films 1 to 29 to form a bonded polarizing plate. The combination is shown in the following table.

Further, the films 1 to 9, 11 to 18, and 22 to 29 of the deuterated cellulose-based film are bonded together using a polyvinyl alcohol-based adhesive; and the film 10 is bonded to a photo-adhesive layer by an easy-adhesion layer. The surface side; and the film 19-21 are bonded by an acrylic adhesive.

Further, the films 1 to 24 and 26 to 28 are such that the in-plane retardation axis and the transmission axis of the polarizer are aligned in parallel; and the films 25 and 29 are in-plane retardation axes and polarizers. The through axes are orthogonal to each other.

23. VA type liquid crystal display device production

(1) Preparation of liquid crystal cell 1

LC-42RX1W (manufactured by SHARP Co., Ltd.) was prepared as a VA type liquid crystal display cell. It is used as the liquid crystal cell 1. When AXOSCAN manufactured by AXOMETRICS Co., Ltd. and an attached software were used to measure Δnd (590) of the liquid crystal cell 1, Δnd (590) was 300 nm.

(2) Preparation of liquid crystal cell 2

(2)-1 Formation of red pixel

<Formation of a hardenable composition layer (coating film)>

By using a slit coating apparatus having a slit head having a slit interval of 100 μm and a coating effective width of 500 mm, the colored photosensitive composition of Example 17 of JP-A-2009-144126 is further made of 0.05 mm yttria beads. The bead disperser super-peak roll machine (manufactured by Shou Industrial Co., Ltd.) was subjected to dispersion treatment for 30 minutes, and the slit was applied to the BM forming surface side of a glass substrate (550 mm × 650 mm) formed on one side of a black matrix (BM). A hardenable composition layer (coating film) is formed.

The slit coating system was used to adjust the interval between the slit and the glass substrate and the discharge amount of the coating liquid so that the film thickness after post-baking was 2.0 μm and the coating speed was 100 mm/sec.

<Exposure, development, washing (rinsing)>

Next, using a hot plate, the obtained hardenable composition layer was dried (prebaked) at 120 ° C for 120 seconds, and then exposed to a gap of 180 μm and exposed at 90 mJ/cm ² using a HITACHI exposure machine LE5565. (illuminance: 20 mW/cm ² ).

The exposed substrate was subjected to showering for 60 seconds in a 1.0% developing solution (25 ° C) of a potassium hydroxide-based developing liquid CDK-1 (manufactured by Fujifilm Electronic Materials Co., Ltd.), and washed with pure water. net.

According to the above, a red pixel portion is formed on the glass substrate. The substrate was post-baked in an oven at 220 ° C for 30 minutes to obtain a glass substrate formed of a red pixel portion.

(2)-2 Formation of the green pixel department

On the glass substrate formed of the red pixel portion, a bead disperser super apex roll machine using 0.05 mm yttria beads as a coloring photosensitive composition of Example 18 of JP-A-2009-144126 was used. The green pixel unit was formed in the same manner as the formation of the red pixel portion, except for the 30-minute dispersion process. The substrate was post-baked in an oven at 220 ° C for 30 minutes to obtain a glass substrate formed of a red pixel portion and a green pixel portion.

(2)-3 Formation of the blue pixel

On the glass substrate formed of the red pixel portion and the green pixel portion, in addition to the coloring photosensitive composition of Example 19 of JP-A-2009-144126, a bead dispersion machine using 0.05 mm yttria beads was used. The blue pixel unit was formed in the same manner as the formation of the red pixel portion, except that the apex roll machine (manufactured by Shou Industrial Co., Ltd.) was subjected to the dispersion treatment for 30 minutes. The substrate was post-baked in an oven at 230 ° C for 30 minutes to obtain a color filter substrate.

It is formed by sputtering a transparent electrode of ITO (Indium Tin Oxide) on the color filter substrate produced above. Next, according to Example 1 of JP-A-2006-64921, a spacer is formed on a portion corresponding to the upper portion of the partition wall (black matrix) on the ITO film. This is used as a front side substrate.

Further, a glass substrate on which a transparent electrode of ITO is prepared is used as a counter substrate, and a transparent electrode for the color filter substrate and the counter substrate is patterned in a PVA mode, and a vertical polyimide is further provided thereon. The alignment film formed.

The liquid crystal cell taken out from the liquid crystal panel "LC-37GX1W" manufactured by SHARP Co., Ltd. is taken out, and the array substrate disposed on the light source side is taken out, and the surface is washed with ethanol, and then the product array substrate is bonded to the opposite side by using the glass oil. The glass side of the substrate. This is used as a rear side substrate.

Then, the sealant of the ultraviolet curable resin is applied by a dispenser method at a position corresponding to the black matrix outer frame provided around the RGB pixel group of the color filter surrounding the front substrate, and the liquid crystal for VA mode is dropped, and After bonding to the rear substrate, the bonded substrate is UV-irradiated, and then heat-treated to cure the sealant. The liquid crystal cell 2 is produced in this manner.

Then, when AXOSCAN manufactured by AXOMETRICS Co., Ltd. and Δnd (590) of the liquid crystal cell 2 produced by the attached software measurement were used, Δnd (590) was 300 nm.

(3) Method for fabricating liquid crystal cell 3

In the method of producing a color filter substrate, the coloring photosensitive composition of Example 17 of JP-A-2009-144126 and the formation of a green pixel portion are used in the formation of the red pixel portion. In the coloring photosensitive composition of Example 18 of the publication No. 2009-144126, the coloring photosensitive composition of Example 19 of JP-A-2009-144126 is used for the formation of the blue pixel portion, and the liquid crystal cell is used. 2 The same method was used to produce the liquid crystal cell 3.

Then, when AXOSCAN manufactured by AXOMETRICS Co., Ltd. and Δnd (590) of the liquid crystal cell 3 produced by the attached software measurement were used, Δnd (590) was 300 nm.

(4) Method for fabricating liquid crystal cell 4

A liquid crystal was produced in the same manner as the liquid crystal cell 2 except that a spacer having a diameter of 16 μm and an average height of 3.0 μm was used for the spacer spacer pattern formed on the portion corresponding to the upper portion of the partition wall on the ITO film on the color filter substrate. Cell 4.

When Δnd (590) of the liquid crystal cell 4 produced by AXOSCAN manufactured by AXOMETRICS Co., Ltd. and the attached software was measured, Δnd (590) was 240 nm.

(5) Method for fabricating liquid crystal cell 5

A glass substrate on which a transparent electrode of ITO was formed was prepared, and a transparent columnar spacer pattern having a diameter of 16 μm and an average height of 3.7 μm was formed on the ITO film on the glass substrate, and patterned by applying a PVA mode to the transparent electrode, and further thereon. An alignment film composed of a vertical polyimide is provided as a front substrate.

The rear substrate was produced in the same manner as the liquid crystal cell 2.

Then, the sealant of the ultraviolet curable resin is applied to the spacer on the pillar of the front substrate, the liquid crystal for VA mode is dropped, and after bonding to the rear substrate, the bonded substrate is UV-irradiated, and then heat-treated. The sealant hardens. The liquid crystal cell 5 is produced in this manner.

Then, when AXOSCAN manufactured by AXOMETRICS Co., Ltd. and Δnd (590) of the liquid crystal cell 5 produced by the attached software measurement were used, Δnd (590) was 300 nm.

(6) Method for producing liquid crystal cell 6 (for reference example)

In the method of producing a color filter substrate, the coloring photosensitive composition of Comparative Example 12 of JP-A-2009-144126 and the formation of a green pixel portion are used in the formation of the red pixel portion. In the coloring photosensitive composition of Comparative Example 13 of the publication No. 2009-144126, the coloring photosensitive composition of Comparative Example 14 of JP-A-2009-144126 is used for the formation of the blue pixel portion, and the liquid crystal cell is used. 2 The same method was used to produce the liquid crystal cell 6.

(7) Calculation of the comparison of the components of the front side substrate and the rear side substrate of the liquid crystal cell produced

The liquid crystal cell 1 is decomposed, and the substrate disposed on the viewing side is used as the front substrate, and the array substrate disposed on the light source side is used as the rear substrate. After the surface is washed with ethanol, the components CR used for the front substrate and the rear substrate are calculated.

A polarizing plate (HLC2-2518, manufactured by SANRITZ Co., Ltd.) is disposed on the backlight of the liquid crystal panel "LC-32GH5" manufactured by SHARP, and the front substrate or the rear substrate of the liquid crystal cells 1 to 5 described above is mounted thereon. The rotating table (SGSP-120YAW, SIGMA optical mechanism) was placed in parallel with the polarizing plate on the light source at intervals of 2 mm. At this time, the wiring of the array of the rear substrate and the black matrix of the front substrate are arranged in line with the polarization axis of the polarizing plate. Further, a polarizing plate (HLC2-2518, manufactured by SANRITZ Co., Ltd.) equipped with a rotary table was placed so that the distance between the polarizing plates was 52 mm, and the normal direction was measured in a dark room using a measuring device (BM5A, manufactured by TOPCON Co., Ltd.). The black display and the white display brightness value are used to calculate the front contrast A (white brightness / black brightness). Here, when the polarizing plate is rotated, when the luminance value is the lowest, the luminance value as the black display and the luminance value when the polarizing plate is rotated by 90 degrees are used as the luminance value of the white display.

Next, in the above-described form, the color filter substrate or the array substrate is removed, and only the luminance values of the black display and the white display of the polarizing plate are determined, and the front contrast B is calculated.

In order to exclude the influence of the front contrast B of the polarizing plate in the frontal contrast A, the component comparison was calculated by the following formula.

Component comparison = 1 / (1/ front contrast A-1 / front contrast B)

Based on the calculated component comparison, the component comparison of the front substrate and the component comparison of the rear substrate were calculated and summarized in the following table.

(7) Production of VA type liquid crystal display device

The polarizing plate was bonded to the outer surface of the two substrates of any one of the above liquid crystal cells by a combination shown in the following table to fabricate a VA liquid crystal display device. The absorption axes of the polarizing plates are orthogonal to each other and attached.

As the light source of each liquid crystal display device to be produced, LC-42RX1W (manufactured by SHARP Co., Ltd.) backlight is used for the liquid crystal cells 1 to 4 and 6, and BGR3 color is used for the liquid crystal cell 5 at 180 Hz. LED, and carry out the following evaluation.

24. Evaluation of VA type liquid crystal display device

The liquid crystal cell 1 was used as a VA type liquid crystal cell, and each of them was combined with a polarizing plate as shown in the following table to fabricate liquid crystal display devices of the examples and the comparative examples, respectively.

(1) Determination of positive contrast

Using a measuring device (BM5A, manufactured by TOPCON Co., Ltd.), the brightness values of the black display and the white display in the normal direction of the panel were measured in a dark room, and the front contrast (white brightness/black brightness) was calculated.

(2) Determination of front contrast

Using a measuring device (BM5A, manufactured by TOPCON Co., Ltd.), the brightness values of the black display and the white display in the normal direction of the panel were measured in a dark room, and the front contrast (white brightness/black brightness) was calculated. At this time, the distance between the measuring device and the panel was set to 700 mm.

Then, the front contrast is calculated based on the front contrast in the reference form and is expressed by the following equation.

Front contrast = positive contrast in the implementation / frontal contrast in the baseline form

In addition, the case where the reference form is in the liquid crystal cell 1 is Comparative Example 10 and the front side contrast is 3060.

(3) Comparison of viewing angles (comparison of oblique directions)

The light leakage rate at the time of black display from the front surface of the apparatus at 45 degrees in the azimuth direction and 60 degrees in the polar angle direction was measured. The smaller the value is, the smaller the light leakage in the oblique direction of 45 degrees is, indicating that the contrast of the display device is good, and the viewing angle characteristics of the liquid crystal display device can be evaluated.

The inadmissibility of the following indicators means that even in the bright room, the light leak can be recognized by the light leakage.

◎: Light leakage cannot be recognized

○: Light leakage is mild

△: Light leakage is medium to severe

△×: Large light leakage (not allowed)

×: Strong light leakage (not allowed)

(4) Color shift when black is displayed

The change in the omnidirectional angular direction (Δuv) at a polar angle of 60 degrees was measured.

The inadmissibility of the following indicators means that even in the bright room, the degree of color change can be recognized.

◎: The color change is very small

○: The color change is mild

△: The change in color taste is moderate

△×: color change (not allowed)

×: There is a strong color change (not allowed)

(5) uneven corners

The corner unevenness was caused by heat treatment of the liquid crystal display device at 50 ° C and 95% RH for 120 hours, and after conditioning for 20 hours at 25 ° C and 60% RH, the backlight was turned on to evaluate the light leakage in black display.

◎: There are no light leaks in 4 corners

○: Among the four corners, there is a faint light leak anywhere.

△: Among the 4 corners, there are light leaks in 2~3 places (not allowed)

△×: There are light leaks in 4 corners (not allowed)

×: There are clear light leaks in 4 corners (not allowed)

The results are shown in the following table.

From the above results, it is understood that the inner protective film having the rear polarizing plate, that is, the first retardation film, the film 9 , 10 , 13 satisfying |Re(590)|≦10 nm and |Rth(590)|≦25 nm In any of the VA type liquid crystal display devices of the embodiments of the present invention according to any one of 15.19 and 20, any one of them has a high frontal contrast. Furthermore, it can be understood that any viewpoints such as viewing angle contrast, color shift at black display, and corner unevenness are good.

On the other hand, in Comparative Example 2 in which the film 7 is used as the inner protective film of the rear polarizing plate, the film 7 contains a film satisfying the characteristics required as the first retardation film, but other than The retardation film (phase difference film 7a) of this characteristic is not satisfied, so the front contrast reduction is understandable.

In addition, Comparative Example 1 and Comparative Example 6 have the same configuration except for the rear side polarizing plate and the front side polarizing plate of Examples 2 and 5, respectively, but there is an unsatisfactory relationship between the rear side polarizer and the liquid crystal cell. The film 2 having the characteristics required for the first retardation film is therefore understandable.

In Example 18, although the front contrast was as high as in Example 1, the viewing angle comparison was lower than that of Example 1. It is generally considered that although the optical characteristics of the film 28 used as the second retardation film satisfy Δnd(590)−70 nm≦Rth ₁ (590)+Rth ₂ (590)≦Δnd(590)-10 nm, Almost the lower limit.

25. Evaluation of VA type liquid crystal display device (characteristic of liquid crystal cell)

Next, in the production of the liquid crystal display device of the second embodiment, a VA liquid crystal display device was produced in the same manner as in Example 2 except that the liquid crystal cells 2 to 5 were used instead of the liquid crystal cell 1, and the evaluation was performed in the same manner as described above. The evaluation results are shown in the following table.

However, regarding the front contrast calculated from the following formula, the reference form is as follows.

Front contrast = positive contrast in the implementation / frontal contrast in the baseline form

The case of the liquid crystal cell 1 is Comparative Example 10 and the front contrast is 3060, the case of the liquid crystal cell 2 is Comparative Example 11 and the front contrast is 3080, the case of the liquid crystal cell 3 is Comparative Example 12, and the front contrast is 2820, and the liquid crystal cell 4 is used. The case of Comparative Example 13 and the front contrast was 2480, and the liquid crystal cell 5 was Comparative Example 14 and the front contrast was 3950.

As a result of the above-mentioned table, it is possible to significantly improve the front contrast even if the member of the front side substrate of the liquid crystal cell substrate is compared with the member of the rear side substrate of which the liquid crystal cells 1 to 5 of 3.0 or more are compared. . The liquid crystal cell 5 used in the embodiment 22 is the same as the liquid crystal cell which is sequentially driven, that is, from the above results, it is understood that the effects of the present invention are remarkable even in the liquid crystal display device which is driven by the feed sequence.

The VA liquid crystal display device produced in the same manner as in Example 2 was similarly evaluated except that the liquid crystal cell 6 was used instead of the liquid crystal cell 1 as a reference example. In the VA liquid crystal display device, the effect of improving the front contrast was not obtained, and the front contrast was small as compared with Example 2 and Examples 19 to 22. This reason is presumed to be because the member contrast of the front substrate of the liquid crystal cell 6 and the member of the rear substrate are compared to 1.7, so that the effect of the present invention is alleviated.

The meaning of the symbols in the figures is as follows.

10. . . Backlight

12, 14. . . Polarized photon

16. . . First retardation film (first phase difference field)

18. . . Second retardation film (second phase difference field)

20, 22. . . Outer protective film

twenty four. . . Substrate

LC. . . VA type liquid crystal cell

PL1. . . Rear polarizer

PL2. . . Front side polarizer

Fig. 1 is a schematic cross-sectional view showing an example of a VA liquid crystal display device of the present invention.

Fig. 2 is a schematic view for explaining the action of the present invention.

10. . . Backlight

12, 14. . . Polarized photon

16. . . First retardation film (first phase difference field)

18. . . Second retardation film (second phase difference field)

20, 22. . . Outer protective film

24, 26. . . Substrate

LC. . . VA type liquid crystal cell

PL1. . . Rear polarizer

PL2. . . Front side polarizer

Claims (13)

A VA liquid crystal display device comprising a front side polarizer, a rear side polarizer, a VA type liquid crystal cell disposed between the front side polarizer and the rear side polarizer, and the rear side polarizer and the VA The first phase difference region composed of one or two or more retardation layers between the liquid crystal cells, the first phase difference region satisfying the following formula: 0 nm ≦ Re ₁ (590) ≦ 10 nm, and | Rth ₁ In the formula (590)|≦25 nm, Re ₁ (λ) means an in-plane hysteresis value (nm) at a wavelength λ nm, and Rth ₁ (λ) means a hysteresis value (nm) in a thickness direction of a wavelength λ nm, wherein the VA type liquid crystal cell based substrate having a front side and a rear substrate and the front substrate member contrast (CR _f) than to the rear side of the substrate member contrast (CR _r) is (CR _f / CR _r) is 3 or more . The VA liquid crystal display device of claim 1, wherein the front side polarizer and the VA type liquid crystal cell have a second phase difference region composed of one or two or more retardation layers, The second phase difference domain satisfies the following formula: 30 nm ≦Re ₂ (590) ≦ 90 nm, and 170 nm ≦ Rth ₂ (590) ≦ 300 nm, where Re ₂ (λ) means an in-plane hysteresis value at a wavelength λ nm (nm), Rth ₂ (λ) means a hysteresis value (nm) in the thickness direction of the wavelength λ nm. The VA liquid crystal display device of claim 2, wherein the first and second phase difference domains satisfy the following formula: Δnd (590) - 70 ≦ Rth ₁ (590) + Rth ₂ (590) In the formula ≦nd(590)-10, d is the thickness (nm) of the liquid crystal layer of the VA type liquid crystal cell, and Δn(λ) is the refractive index anisotropy of the liquid crystal layer of the VA type liquid crystal cell at the wavelength λ. Δnd(λ) means the product of Δn(λ) and d. The VA liquid crystal display device according to claim 1, wherein the first phase difference field is composed of a deuterated cellulose film or a deuterated cellulose film. The VA type liquid crystal display device of claim 4, wherein the deuterated cellulose-based film contains at least one hysteresis value Rth _{1 in the} thickness direction within a range satisfying the following formulas (I) and (II). Reduced compound, (I) (Rth ₁ [A]-Rth ₁ [0]) / A ≦ -1.0 (II) 0.01 ≦ A ≦ 30 (Rth ₁ [A]: a compound containing A% which lowers Rth ₁ Hysteresis value (nm) in the thickness direction of the film, Rth ₁ [0]: hysteresis value (nm) in the thickness direction of the film containing no compound which lowers Rth ₁ , and A: quality of the film raw material polymer as 100 The mass (%) of the compound at the time). The VA type liquid crystal display device of claim 4, wherein the deuterated cellulose-based film is contained in deuterated cellulose having a thiol substitution degree of 2.85 to 3.00, relative to the solid content of deuterated cellulose. At least one compound having an in-plane hysteresis value Re ₁ (λ) and a thickness direction hysteresis value Rth ₁ (λ) of 0.01 to 30% by mass. At least one thin film such as a VA type liquid crystal range patent Paragraph fourth display device, wherein the acylated cellulose film with respect to the acyl-based cellulose solids content, contains 0.01 to 30% by mass | Re ₁ (400)-Re ₁ (700)| and | Rth ₁ (400)-Rth ₁ (700)|Reduced compound. A VA liquid crystal display device according to claim 1, wherein the first phase difference region is composed of an acrylic polymer film or an acrylic polymer film. The VA type liquid crystal display device of claim 8, wherein the first phase difference region is made of acrylic acid containing at least one unit selected from a lactone ring unit, a maleic anhydride unit, and a glutaric anhydride unit. It is composed of a polymer-based acrylic polymer film or has the acrylic polymer film. A VA liquid crystal display device according to claim 2, wherein the second phase difference field is composed of a deuterated cellulose film or a deuterated cellulose film. The VA liquid crystal display device according to the second aspect of the invention, wherein the second phase difference region is composed of a cyclic olefin polymer film or a cyclic olefin polymer film. For example, in the VA type liquid crystal display device of claim 1, the front contrast is 1500 or more. For example, the VA type liquid crystal display device of claim 1 is a backlight unit that sequentially emits three primary colors of light independently, and is driven by a field sequential driving method.